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United States Air Force Environmental Restoration Program FINAL RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA Homestead Air Reserve Base, Florida September 2006
Transcript
Page 1: RECORD OF DECISION FOR OPERABLE UNIT 25 HUSH ...1 HOMESTEAD AIR RESERVE BASE HOMESTEAD, FLORIDA RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA 1.0 DECLARATION 1.1 Site

United States Air Force

Environmental Restoration Program

FINAL

RECORD OF DECISION FOR

OPERABLE UNIT 25 – HUSH HOUSE AREA

Homestead Air Reserve Base, Florida

September 2006

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HOMESTEAD AIR RESERVE BASE

RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA

FINAL

Prepared by Booz Allen Hamilton

Atlanta, GA

September 2006

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TABLE OF CONTENTS

SECTION PAGE

LIST OF ACRONYMS ...................................................................................................................................... iii 1.0 DECLARATION ........................................................................................................................1

1.1 SITE NAME AND LOCATION.......................................................................................................... 1 1.2 STATEMENT OF BASIS AND PURPOSE ....................................................................................... 1 1.3 ASSESSMENT OF THE SITE ............................................................................................................ 1 1.4 DESCRIPTION OF THE SELECTED REMEDY............................................................................ 2 1.5 STATUTORY DETERMINATIONS ................................................................................................. 5 1.6 ROD DATA CERTIFICATION CHECKLIST ................................................................................. 5 1.7 AUTHORIZING SIGNATURES AND SUPPORT AGENCY ACCEPTANCE OF REMEDY... 7

2.0 DECISION SUMMARY .............................................................................................................8 2.1 SITE NAME, LOCATION, AND DESCRIPTION ........................................................................... 8 2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES.................................................................. 8 2.3 COMMUNITY PARTICIPATION................................................................................................... 10 2.4 SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION..................................... 12 2.5 SITE CHARACTERISTICS.............................................................................................................. 12

2.5.1 Nature and Extent of Contamination.......................................................................................13 2.5.2 Contaminant Fate and Transport..............................................................................................17

2.6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USES ............................... 19 2.7 SUMMARY OF SITE RISKS............................................................................................................ 19

2.7.1 Summary of Human Health Risk Assessment........................................................................20 2.7.2 Summary of Ecological Risk Assessment ................................................................................25

2.8 REMEDIAL ACTION OBJECTIVES ............................................................................................. 25 2.9 DESCRIPTION OF ALTERNATIVES............................................................................................ 26

2.9.1 Alternative 1 – No Further Action............................................................................................26 2.9.2 Alternative 2 – Land Use Controls ...........................................................................................27 2.9.3 Alternative 3 – Excavation and Off-Site Disposal ..................................................................27

2.10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES ....................................... 27 2.10.1 Threshold Criteria .......................................................................................................................28 2.10.2 Balancing Criteria........................................................................................................................29 2.10.3 Modifying Criteria ......................................................................................................................30 2.10.4 Comparison of Alternatives ......................................................................................................32

2.11 PRINCIPAL THREAT WASTES..................................................................................................... 33 2.12 SELECTED REMEDY....................................................................................................................... 33 2.13 STATUTORY DETERMINATIONS ............................................................................................... 36 2.14 DOCUMENTATION OF SIGNIFICANT CHANGES................................................................... 38

3.0 RESPONSIVENESS SUMMARY............................................................................................39

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LIST OF FIGURES

Figure Title Page

2-1 IRP Site Locations ......................................................................................................................9

2-2 Sample Locations and Excavation Area................................................................................11

LIST OF TABLES

Table Title Page

1-1 Soil Cleanup Target Levels for Constituents of Concern at Operable Unit 25..................3

1-2 Carcinogenic Risk and Noncarcinogenic Hazard Estimates for OU-25............................3

2-1 Summary of Operable Unit 25 History ...................................................................................8

2-2 Constituents of Concern in Soil Exceeding Soil Cleanup Target Levels (SCTLs), 1994 Confirmation Sampling..................................................................................................14

2-3 Constituents of Concern in Soil Exceeding Soil Cleanup Target Levels (SCTLs), 1996 Site Investigation.............................................................................................................15

2-4 Constituents of Concern in Ground Water Exceeding Ground-Water Cleanup Target Levels, Ground-Water Monitoring Results..............................................................18

2-5 Summary of Constituents of Concern in Soil Exceeding Soil Cleanup Target Levels .........................................................................................................................................21

2-6 Risk Evaluation Exposure Assumptions ..............................................................................23

2-7 Carcinogenic Risk and Noncarcinogenic Hazard Estimates for OU-25..........................24

2-8 Soil Cleanup Target Levels for COCs at OU 25...................................................................26

2-9 Comparison of Alternatives ...................................................................................................32

APPENDICES

Appendix Title

A References

B Regulatory Correspondence

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LIST OF ACRONYMS

AFB Air Force Base AFRC Air Force Reserve Command ARAR Applicable or Relevant and Appropriate Requirement ARB Air Reserve Base BGP Base General Plan bgs below ground surface CERCLA Comprehensive Environmental Response, Compensation, and Liability Act COC Constituent of Concern CRP Community Relations Plan DERM Department of Environmental Resources Management DoD Department of Defense EPA U.S. Environmental Protection Agency EPC exposure point concentration FAC Florida Administrative Code FDEP Florida Department of Environmental Protection FFA Federal Facilities Agreement FS feasibility study GCTL ground-water cleanup target level IRA interim remedial action kg kilogram LUC land use control MCL maximum contaminant level mg milligrams NCP National Oil and Hazardous Substances Pollution Contingency Plan NPL National Priorities List OU operable unit PAH polynuclear aromatic hydrocarbon PCB polychlorinated biphenyl RAB Restoration Advisory Board RAO remedial action objective RCRA Resource Conservation and Recovery Act RME reasonable maximum exposure ROD record of decision SARA Superfund Amendments and Reauthorization Act SCTL soil cleanup target level SI Site Investigation SVOC semivolatile organic compound SWMU solid waste management unit µg micrograms UCL upper confidence limit VOC volatile organic compound

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HOMESTEAD AIR RESERVE BASE HOMESTEAD, FLORIDA

RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA

1.0 DECLARATION

1.1 Site Name and Location

Homestead Air Reserve Base (ARB) (U.S. Environmental Protection Agency [EPA] Identification Number [ID No.] FL7570024037), is located within southeastern Miami-Dade County near the southern tip of peninsular Florida. The installation is located near U.S. Highway 1, approximately 25 miles southwest of Miami, immediately east of the City of Homestead boundary, and 2 miles west of Biscayne Bay. Operable Unit (OU) 25 is located in the extreme southern portion of Homestead ARB, between the runway and the southern boundary of the installation. This area of the installation is undeveloped and is isolated from the main portion of Homestead ARB. The runway is located approximately 1,200 feet (ft) northwest of the site.

1.2 Statement of Basis and Purpose

Homestead Air Force Base (AFB) was placed on the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) on 30 August 1990. This resulted in the adoption of a Federal Facilities Agreement (FFA) between the EPA, the State of Florida, and the U.S. Air Force, which was finalized in early 1991. This Record of Decision (ROD) is being issued by the U.S. Air Force Reserve Command (AFRC), which is the lead agency for environmental restoration activities at Homestead ARB under CERCLA and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The final remedy for OU-25 was co-selected by AFRC and EPA Region IV, with the concurrence of the Florida Department of Environmental Protection (FDEP).

This ROD presents the Selected Remedy for OU-25 at Homestead ARB, in Miami-Dade County Florida, which was chosen in accordance with CERCLA regulations, as amended by the Superfund Amendments and Reauthorization Act (SARA), and, to the extent practicable, the NCP. This decision is based on the Administrative Record file for this site.

1.3 Assessment of the Site

The response action selected in this ROD is necessary to protect the public health or welfare or the environment from actual or threatened releases of hazardous substances into the environment.

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1.4 Description of the Selected Remedy

OU-25 is one of 31 sites that are part of the cleanup strategy at the former Homestead AFB. Two OUs were transferred to the Florida petroleum program, final remedial actions have not been selected for eight other OUs, and no action decisions have been made for six OUs. OU-25 has been investigated and remediated independently from all other OUs at Homestead AFB. The remedy selected in this ROD applies only to the portions of the OU-25 site where soil contains contaminants with concentrations greater than the FDEP soil cleanup target levels (SCTLs) shown in Table 1-1. No other media at OU-25 have been impacted by releases of contaminants. Figure 2-2 identifies the estimated extent of soil containing contaminant concentrations exceeding residential SCTLs, which will require LUCs. The selected remedy for OU-25 is not applicable to any other site or OU at the installation.

Approximately 815 cubic yards of soil at OU-25 are estimated to be contaminated with polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals at concentrations that exceed the unrestricted use and unlimited exposure criteria represented by the residential SCTLs, shown in Table 1-1.

As part of the OU-25 risk evaluation, exposure point concentrations (EPCs) were calculated for contaminants of concern (COCs). EPCs represent a conservative estimate of the concentration of COCs in OU-25 soil. As shown in Table 1-1, EPCs for total PAHs and benzo(a)pyrene exceeded their respective FDEP commercial/industrial SCTLs. EPCs for all other COCs were less than their respective FDEP commercial/industrial SCTLs. The EPC for arsenic exceeded the residential SCTL but was less than the base-specific background concentration of 10 mg/kg. As a result, remedial action is not necessary to address arsenic in soil at OU-25.

Further evaluation of the risks posed by exposure to OU-25 soil by current and future receptors was performed. Based on an evaluation of the current and reasonably anticipated future use of the OU-25 site, the population group identified as current and future potentially exposed receptors are commercial/industrial workers. The OU-25 risk evaluation also estimated risk posed to hypothetical future construction workers and on-site residents. Table 1-2 provides results of the OU-25 risk evaluation.

For known or suspected carcinogens, acceptable exposure levels are generally concentration levels that represent an excess upper bound life-time cancer risk to an individual of between 1 x 10-4 and 1 x 10-6 using information on the relationship between dose and response. In addition, EPA risk assessment guidance indicates that acceptable exposure levels for noncarcinogens correspond to a cumulative noncarcinogenic hazard index of less than 1.0. Based on a comparison of the calculated risks and hazards for potentially exposed receptors at OU-25 with the NCP goals, contaminated soil does not pose an unacceptable carcinogenic risk to commercial/industrial workers. The carcinogenic risk level for commercial/industrial workers, construction workers, or residents do not indicate an unacceptable risk, according to EPA and Air Force policy and guidance, because the estimated risks for these receptor populations are less than the upper limit of EPA’s target risk range of 1 x 10-4. In addition, OU-25 soil does not pose an unacceptable noncarcinogenic hazard to commercial/industrial workers because the hazard index is less than 1.0.

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Table 1-1 Soil Cleanup Target Levels for Constituents of Concern at Operable Unit 25

FDEP Soil Cleanup Target Levels1 Constituents of Concern Units Residential Commercial/Industrial

Exposure Point Concentrations2

Total PAHs3 µg/kg4 100 700 3,417.85 Benzo(a)pyrene µg/kg 100 700 1,859.7 Dibenz(a,h)anthracene µg/kg − − 8.34 Naphthalene µg/kg 2,000 300,000 1,775.4 PCB mixture µg/kg 500 2,600 423.3 Antimony mg/kg6 27 370 12.51 Arsenic mg/kg 2.1 12 9.4 Barium mg/kg 120 130,000 61.93 Lead mg/kg 400 1,400 266.4

Notes: 1. Chapter 62-777 of the Florida Administrative Code (FAC), dated 17 April 2005 2. EPCs were calculated as the 95% Upper Confidence Limit (UCL) on the mean using EPA’s ProUCL software. 3. PAHs are evaluated as the sum of the benzo(a)pyrene toxicity equivalents for the individual PAHs. 4. µg/kg = micrograms per kilogram 5. Exposure point concentrations (EPCs) were calculated for PAHs as the sum of the benzo(a)pyrene toxicity equivalents

for the carcinogenic PAHs. 6. mg/kg = milligrams per kilogram

Table 1-2 Carcinogenic Risk and Noncarcinogenic Hazard Estimates for OU-25

The noncarcinogenic hazard for both construction workers and on-site residents exceeded the 1.0 target threshold. As a result, impacted soil at OU-25 may pose an unacceptable noncarcinogenic hazard to hypothetical construction worker and residential receptors.

While FDEP indicated they could not agree with the use of the 1 x 10-4 target risk level, it concurred with the overall conclusions of the risk evaluation and agreed that the selected remedy for OU-25 was appropriate. Section 2.10.3 provides additional discussion of FDEP’s rationale for supporting the selected remedy for OU-25. The COCs in OU-25 soil, listed in Table 1-1, are not considered principal threat wastes because they are present at concentrations that are not greatly above the SCTLs; they do not pose an excess cancer risk greater than the acceptable risk range if exposure to the contaminants were to occur; and they are relatively immobile in soil. As a result, aggressive removal and/or treatment of the contamination is not warranted and only limited action is necessary to protect human health.

The selected remedy for OU-25 is Land Use Controls (LUCs), which include:

Receptor Risk Hazard Index Resident 8.04 x 10-5 1.5 Commercial/Industrial Worker 2.27 x 10-5 0.1 Construction Worker 6.98 x 10-5 1.1

Principal Threat Wastes are source materials (e.g., contaminated soil or ground

water) that contain highly toxic or highly mobile chemicals, which generally cannot be

contained in a reliable manner or would present a significant risk to human health

and the environment should exposure occur.

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• Use Restrictions – Residential use will be prohibited on portions of the OU-25 property containing contaminated soil at concentrations greater than unrestricted use and unlimited exposure criteria represented by the residential SCTLs shown in Table 1-1. The residential use restrictions will be implemented to prohibit property users from using the property for residential purposes, hospitals for human care, public or private schools or day care centers for persons under 18 years of age. Use restrictions will ensure that the future land use of the property remains commercial/industrial and does not change to residential use. Figure 2-2 identifies the estimated extent of soil containing contaminant concentrations exceeding residential SCTLs and the area that will be addressed by LUCs, which is identified by the dashed box surrounding the concrete pad.

• Digging Restrictions – Excavation of OU-25 soil containing concentrations of contaminants greater than the industrial SCTLs shown in Table 1-1 will be managed to ensure that unacceptable exposure to the contaminants does not occur. These restrictions will be enforced through the dig permit system and construction review process that is currently in place throughout Homestead ARB. No construction or digging is allowed without prior approval by the Base Engineer in the form of a dig permit or other approval as required by applicable Air Force instruction and procedures. The Base Civil Engineer will not approve permits for activities inconsistent with LUCs.

• Contaminated Soil Management Restrictions – LUCs will be implemented to require that any contaminated soil that is excavated at OU-25 will be properly managed on site and that any contaminated soil transported off site will be managed in accordance with applicable RCRA regulations.

LUCs will allow the property to continue to be used in the current manner and will allow future development of the property for commercial/industrial purposes, as long as contaminated soil is properly managed. Residential use restrictions will ensure that the property is not redeveloped for residential use. Digging restrictions will prevent direct contact with contaminated surface and subsurface soils, prevent emissions of contaminant particles entrained on dust, and ensure proper personnel protection and waste management of contaminated soil that is excavated in the future.

Use restrictions will be identified in the Base General Plan (BGP) and implemented, monitored, maintained, reported on, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personnel at the installation through existing land-use management programs. Use restrictions will ensure that the future land use of the property remains commercial/industrial and does not change to residential use. LUCs will remain in place until concentrations decline below unrestricted use and unlimited exposure criteria represented by the residential SCTLs.

These LUCs will be implemented, monitored, maintained, and enforced at OU-25 in conjunction with LUCs at other OUs at Homestead ARB to ensure that LUCs are consistently and efficiently implemented as part of the cleanup strategy at Homestead ARB. Homestead ARB Environmental Flight Office personnel will monitor the contaminated areas of OU-25 to ensure that LUCs are not breached and remain protective. Annual reports summarizing the results of the LUC monitoring will be submitted to FDEP and EPA. Homestead ARB Environmental

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Flight personnel will promptly notify EPA and FDEP if any activity that is inconsistent with the LUCs or may interfere with their effectiveness is observed at OU-25. Homestead ARB Environmental Flight personnel will notify and seek concurrence from EPA and FDEP prior to termination or modification of the LUCs and will notify EPA and FDEP prior to transfer of the property.

1.5 Statutory Determinations

The AFRC expects the selected remedy to satisfy the following statutory requirements of CERCLA §121(b). The selected remedy is protective of human health and the environment, complies with federal and state requirements that are applicable or relevant and appropriate to the remedial action, is cost effective, and utilizes permanent solutions and alternative technologies to the maximum extent practicable.

The selected remedy for OU-25 does not satisfy the statutory preference for treatment as a principal element of the remedy for the following reasons:

No principal threat wastes are present for which aggressive treatment is warranted

LUCs provide comparable protection of human health and are more easily implemented than other remedial alternatives considered in the Streamlined Feasibility Study (FS). They are also more cost-effective because they will achieve the same level of protection of current and future receptors at a significantly reduced cost.

Because this remedy will result in hazardous substances, pollutants, or contaminants remaining on site above levels that allow for unlimited use and unrestricted exposure, a statutory review will be conducted within five years after initiation of remedial action to ensure that the remedy is, or will be, protective of human health and the environment. Five-year reviews will continue until contaminant concentrations in soil have decreased to levels that allow for unlimited use and unrestricted exposure. This requirement is pursuant to CERCLA §121 and the NCP 40 CFR 300.430(f)(4)(ii).

1.6 ROD Data Certification Checklist

The following information is included in the Decision Summary section of this ROD:

COCs and their respective concentrations—Sections 2.5 and 2.7

Potential risks posed by the COCs—Section 2.7

Cleanup levels established for COCs and the basis for these levels—Section 2.8

How source materials constituting principal threats are addressed—Section 2.11

Current and reasonably anticipated future land use assumptions and current and potential future beneficial uses of ground water used in the risk assessment and the ROD—Section 2.6

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Potential land and ground-water use that will be available at the site as a result of the selected remedy—Section 2.12

Estimated costs and the number of years over which the cost estimates are projected—Section 2.10

Key factors that led to selecting the remedy—Section 2.10

Additional information can be found in the Administrative Record file for this site, which can be accessed at https://afrpaar.afrpa.pentagon.af.mil/docsearch/newdocsearchform.asp.

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1.7 Authorizing Signatures and Support Agency Acceptance of Remedy

The following signatures certify that all parties agree to the contents of this ROD and the selected remedy.

L

Randall ~ 3 a i c o n 7 Colonel, USAFR Commander, 482d Fighter Wing Homestead Air Reserve Base, Florida

Bever . Banister

2VA 68 Date

?- Zb'Ob Date

~ c t i n g Director, Waste Management Division U.S. Environmental Protection Agency, Region 4

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2.0 DECISION SUMMARY

2.1 Site Name, Location, and Description

Homestead ARB (EPA ID No. FL7570024037) is located within southeastern Miami-Dade County near the southern tip of peninsular Florida. The installation is located near U.S. Highway 1, approximately 25 miles southwest of Miami, immediately east of the City of Homestead boundary, and 2 miles west of Biscayne Bay.

OU-25 is located within the Hush House Area (Engine Test Cell Facility) and was formerly referred to as solid waste management unit (SWMU) 59. The site is located in the extreme southern portion of the Homestead ARB, as depicted in Figure 2-1, and occupies an area of approximately 0.4 acres, including the hardstand pad that was previously used for aircraft engine testing. This area of the installation is undeveloped and lies on the far side of the runway, isolated from the main portion of Homestead ARB.

The site itself is a level concrete pad surrounded by a large brush and grass area that is regularly mowed. Figure 2-2 illustrates the site layout and identifies the OU-25 boundary. The concrete pad was originally constructed and formerly used for testing jet engines. However, it has not been used for this purpose since the mid-1980s. More recently, it also was used to temporarily stage and consolidate a variety of materials and waste collected from around Homestead AFB after Hurricane Andrew in 1992. Materials and wastes reportedly staged in the area included pesticides, herbicides, paint, paint thinners, waste and lube oils, and contaminated soil. With the exception of its brief use in 1992, the site has not been used for any purpose since its use as an engine test cell was discontinued.

2.2 Site History and Enforcement Activities

Homestead AFB was placed on the NPL on 30 August 1990. This resulted in the adoption of an FFA between the EPA, the State of Florida, and the U.S. Air Force, which was finalized in early 1991.

A list of important historical events and relevant dates in the site chronology are shown in Table 2-1. The identified events are illustrative, not comprehensive.

Table 2-1 Summary of Operable Unit 25 History

Event Date Aircraft Engine Testing Prior to mid-1980s Material/Waste Storage 1992 Confirmation Sampling 1994 Voluntary Interim Remedial Action (IRA) 1996 Site Investigation (SI) 1996 Ground-Water Monitoring 1997, 1998, 2001

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FIGURE 2-1

IRP Site Locations

Homestead ARB, Florida

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OU-25

LEGEND

– – – Installation Boundary

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A preliminary investigation of OU-25 was completed in 1994 as part of a basewide Confirmation Sampling Program (Woodward-Clyde, 1995). Based on the results of this investigation, an IRA was completed in January 1996 to remove soil containing elevated concentrations of lead, chromium, arsenic, and barium from one location (OHM, 1998). An SI was performed in 1996 to further investigate the area (Woodward-Clyde, 1997), and ground- water monitoring was conducted in 1997, 1998, and 2001 (Versar, 1998; IT, 2001). Figure 2-2 illustrates the locations of samples collected during these investigations.

Based on the results of these investigations, potential final remedy alternatives were evaluated as part of a Streamlined FS for OU-25 in 2006 (Booz Allen, 2006). The analysis conducted in the FS provides the basis for the final remedy identified in this ROD. The Final FS for OU-25 was submitted to EPA and FDEP for review, and letters of approval were received on 22 February 2006 and 20 February 2006, respectively. No substantial comments or concerns with the final FS for OU-25 were raised by EPA. FDEP commented that FAC § 62-780 should be listed and considered as an Applicable or Relevant and Appropriate Requirement (ARAR). Based on this comment, FAC § 62-780 was added to the ARAR analysis. No other substantial comments or concerns with the final FS for OU-25 were raised by FDEP. The Miami-Dade County Department of Environmental Resources Management (DERM) also provided comments on the Streamlined FS, which were considered in preparing this ROD.

2.3 Community Participation

The AFRC has a public participation program at Homestead ARB to promote public understanding of the cleanup process and its results, and to ensure that the community’s concerns are solicited, considered, and thoroughly addressed. The backbone of this program is the Community Relations Plan (CRP), which assesses the public’s level of knowledge, interest, and information needs by conducting community interviews and researching local social, demographic, economic, and political information. The CRP recommended compatible public involvement strategies that included a Restoration Advisory Board (RAB), newsletters, fact sheets, an information repository, and public meetings at project milestones.

RABs are a joint creation of the Department of Defense (DoD) and the EPA and are a vehicle for community input during environmental restoration. A RAB was formed for Homestead AFB in October 1993 and meets routinely. Community members of the RAB exchange information and discuss restoration issues with the government representatives, which include representatives from the Air Force, the EPA, and the FDEP.

RAB meetings provide opportunities for direct public participation. Presentation topics include current investigations, results, plans for the environmental restoration program, and current issues. All RAB meetings are open to the public and include a public comment period for the audience members to ask questions and express opinions and/or concerns.

For the purposes of final remedy selection, the AFRC solicited additional public input about the specific issues surrounding the proposed remedy for OU-25. To accomplish this, the AFRC developed a Proposed Plan for OU-25 and made it available for public review and comment.

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SOURCE: Final Report, Site Investigation, AOC 1, AOC 3, AOC 5, OU 19, OUs 20/21, OU 25, O/WS 206. Woodward-Clyde, April 1997.

FIGURE 2-2

OU-25, Hush House AreaSample Locations and Excavation Area

Homestead ARB, Florida

OU-25 LUC Boundary

NOTE: Sample locations designated by yellow triangles identify locations where sample results exceeded residential SCTLs. Locations designated by orange squares identify locations where sample results exceeded commercial/industrial SCTLs.

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The Proposed Plan described:

The contaminants of concern at the site and the potential risks they pose to human health and the environment.

Final remedy alternatives that were considered for the site and a summary of the evaluation of alternatives that was conducted in the FS.

The preferred final remedy for the site and the means by which it is expected to protect human health and the environment.

The AFRC’s interest in receiving public input on the proposed remedy, the location where the documents were available for review, and methods by which public input could be provided.

A formal comment period was conducted between 03 April and 03 May 2006. During this period, the Proposed Plan and other historical documents, such as the FS, were made available for public review at the at the Homestead Branch of the Miami-Dade County Library located at 700 N. Homestead Boulevard in Homestead, Florida. In addition, a public meeting was held on 20 April 2006, from 7:00 to 8:00 p.m. at the City Council Chamber Room in City Hall, located at 790 Homestead Boulevard, Homestead, Florida, where AFRC representatives were available to discuss the proposed remedy for OU-25 and respond directly to public comments and questions. As summarized in the Responsiveness Summary, which can be found in Section 3.0 of this ROD, no public comments were received during the comment period and no members of the public attended the public meeting.

2.4 Scope and Role of Operable Unit or Response Action

The remedial action for OU-25 is one component of the overall cleanup efforts that are being completed at Homestead AFB. This remedial action is the final remedy for OU-25 and will address the residual contamination that remains at OU-25, as described in Section 2.5. No principal threat wastes are present for which aggressive removal or treatment is warranted. OU-25 is one of 31 sites that are part of the cleanup strategy at the former Homestead AFB. Two OUs were transferred to the Florida petroleum program, final remedial actions have not been selected for eight other OUs, and no action decisions have been made for six OUs. The remedial action for OU-25 is not intended to address contamination at any other OU, each of which is being addressed independently. LUCs will be implemented, monitored, maintained, and enforced at OU-25 in conjunction with LUCs at other OUs at Homestead ARB to ensure consistent and efficient implementation.

2.5 Site Characteristics

OU-25 consists of approximately 0.4 acres of land, including the hardstand pad near former Building 814. The hardstand pad is a square concrete pad, with dimensions of approximately 135 ft by 135 ft, that was used to secure aircraft for engine testing prior to construction of the Hush Houses in the mid-1980s. Later, it also was used to stage and consolidate a variety of

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materials and waste collected from around the installation after Hurricane Andrew in 1992 (Woodward-Clyde, 1997). Grassy fields surround the pad on the north, east, and southeast. Heavy brush is located to the south, west, and northwest of the pad. Further to the south and west, access is restricted by the Boundary Canal system and the perimeter security fence, which is a chain-link fence posted with “No Trespassing” warning signs. An earthen berm is located between the perimeter fence and the Boundary Canal. As a result, access to the site is effectively limited to authorized AFRC personnel and contractors.

The surface topography of the site is relatively flat, with elevations ranging from 2 ft above mean seal level (ft-msl) to 10 ft-msl. Surface soil at Homestead ARB is typically less than 6 inches thick and consists of native marl, weathered limestone bedrock, or imported fill. The water table occurs at depths ranging from 0 to 5 ft below ground surface (bgs); however, the depth is heavily influenced by season and recent rainfall. Although the general direction of ground-water flow within the shallow aquifer beneath Homestead ARB is southeasterly toward Biscayne Bay, the hydraulic gradients throughout the base are very flat. As a result, local ground-water flow directions are strongly influenced by rainfall and the presence of the drainage canal system along the base boundary (Boundary Canal).

2.5.1 Nature and Extent of Contamination

Soil. A total of 7 surface and 12 subsurface soil samples were collected from beneath and surrounding the hardstand pad during the investigations in 1994 and 1996, as shown on Figure 2-2. The investigations identified the presence of elevated concentrations of PAHs, naphthalene, PCBs, and metals around the perimeter of the pad. Data from these sampling events are presented in Tables 2-2 and 2-3.

During the voluntary IRA in 1996, approximately 27.7 tons of contaminated soil were excavated from an area approximately 15 ft long, 15 ft wide, and 2 ft deep, centered on the location of surface soil sample SS-0002, and disposed of off site. Follow-up confirmation sampling performed in 1996 indicated that the excavation of soil successfully removed the elevated levels of contamination in the northeast corner of the hardstand (OHM, 1998).

Overall, post-IRA confirmation sampling indicates that there is a limited quantity of soil containing concentrations of contaminants that exceed commercial/industrial SCTLs. However, soil contamination exceeding unrestricted use and unlimited exposure criteria, represented by the residential SCTLs, is more widespread. Sample locations at OU-25 that exceeded the residential and commercial/industrial SCTLs are identified in Figure 2-2.

The lateral and vertical dimensions of the soil contamination exceeding the residential SCTLs were estimated based on the location and depth of historical samples and multiplied to derive volume estimates for the contaminated soil. Following completion of excavation activities, it is estimated that approximately 815 cubic yards of PAH-, naphthalene-, PCB-, and metals-contaminated soil remain around the perimeter of the pad. A more detailed description of the extent of contamination exceeding residential and commercial/industrial SCTLs is provided in the Streamlined FS.

Ground water. During the investigations in 1994 and 1996, ground-water samples were collected from 22 direct-push borings and two monitoring wells, as shown on Figure 2-2.

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TABLE 2-2 OPERABLE UNIT 25 – HUSH HOUSE AREA

CONSTITUENTS IN SOIL EXCEEDING SOIL CLEANUP TARGET LEVELS (SCTLs) 1994 CONFIRMATION SAMPLING

(WOODWARD-CLYDE, 1995)

SCTL1

Constituent Residential Commercial/

Industrial

Base-Specific Soil Cleanup

Goals2,3

SS-0002-04,5 0 ft bgs6

25-Apr-94

SS-0003-0 0 ft bgs

25-Apr-94

SS-0004-0 0 ft bgs

25-Apr-94

SS-0005-0 0 ft bgs

25-Apr-94

SB-0001-44,7 2-4 ft bgs 10-Jun-94

SB-0002-47 2-4 ft bgs 10-Jun-94

Polycyclic Aromatic Hydrocarbons (µg/kg)8 PAHs9 100 700 − ND10 5,47411,12 5,284 305 ND ND

Benzo(a)anthracene − − − ND 3,100J13 3,300 170J ND ND Benzo(a)pyrene 100 700 1,500 ND 4,100J 3,200 210J ND ND Benzo(b)fluoranthene − − − ND 4,000J 4,900 290J ND ND Benzo(k)fluoranthene − − − ND 3,800J 2,900 280J ND ND Chrysene − − − ND 4,100J 3,800 290J ND ND Dibenz(a,h) anthracene − − 1,500 ND ND 780 ND ND ND Indeno(1,2,3-cd)pyrene − − − ND 2,800J 1,900 210J ND ND

Organochlorine Pesticides (µg/kg) PCB (Arochlor Mixture) 500 2,600 − ND ND ND ND ND 200

Inorganics (mg/kg)8 Antimony 27 370 − ND ND ND ND 27.4 26.8 Arsenic 2.1 12 10 8.5 3.8 5.7 8.5 0.28 ND Barium 120 130,000 − 470 23.5 129 118 4.6 8.3 Chromium 210 470 − 229 15.9 31.3 22.8 4.7 5.1 Lead 400 1,400 − 1,400 40 98.1 74.9 0.48 0.63

Notes: 1. SCTLs are based on Chapter 62-777, FAC criteria dated 17 April 2005.

2. The Base-Specific Soil Cleanup Goals for PAHs were agreed upon at the 19 September 1996 BCT meeting, based on the findings presented in “A Practical Approach for the Development of Typical Basewide PAH Concentrations Not Related to Waste Handling Practices for Use in Risk Management Decisions,” (Woodward-Clyde, 1996).

3. The Base-Specific Soil Cleanup Goal for arsenic is based on the Arsenic Background Study completed in November 1996 (AFBCA, 1996). 4. Sample Type: SS = surface soil sample. SB = soil boring. 5. Diagonal cross-hatching denotes sample locations that were excavated during the removal action in 2000 6. bgs = below ground surface. 7. Samples SB-0001-4 and SB-0002-4 were collected from monitoring wells MW1 and MW2, respectively. 8. Units: µg/kg = micrograms per kilogram; mg/kg = milligrams per kilogram. 9. PAHs were calculated as the sum of the benzo(a)pyrene equivalents for the carcinogenic PAHs. 10. ND = Not detected above the method detection limit. 11. Bold text denotes results that exceed the residential SCTL. 12. Dark shaded cells denote results that exceed the commercial/industrial SCTL. 13. Qualifiers: J = The value is estimated.

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TABLE 2-3

OPERABLE UNIT 25 – HUSH HOUSE AREA CONSTITUENTS IN SOIL EXCEEDING SOIL CLEANUP TARGET LEVELS (SCTLs)

1996 SITE INVESTIGATION (WOODWARD-CLYDE, 1997)

SCTL1

Constituent Residential Commercial/

Industrial

Base-Specific Soil Cleanup

Goals2,3

SS-0006-04 0 ft bgs5

15-Jan-96

SS-0007-0 0 ft bgs

15-Jan-96

SB-0003-04 0 ft bgs

15-Jan-96

SB-0004-0 0 ft bgs

15-Jan-96

SB-0004-2 2 ft bgs

15-Jan-96 Polycyclic Aromatic Hydrocarbons (µg/kg)6

PAHs7 100 700 − 1,4328,9 504 2,522 250 181 Benzo(a)anthracene − − − 730 300J 2,100 160 ND10 Benzo(a)pyrene 100 700 1,500 790 320J11 1,400 140 140J Benzo(b)fluoranthene − − − 1,000 410J 2,700 240 130J Benzo(k)fluoranthene − − − 770 400J 1,000 150 130J Chrysene − − − 870 400J 1,700 190 66J Dibenz(a,h) anthracene − − 1,500 300J 55J 430J 43 ND Indeno(1,2,3-cd)pyrene − − − 910 180J 1,100 120 150J

Organochlorine Pesticides (µg/kg) PCB (Arochlor Mixture) 500 2,600 − 1,300P11 ND 400 69 ND

Inorganics (mg/kg)6 Antimony 27 370 − 5.7 4.3 4.4J ND ND Arsenic 2.1 12 10 10.2 3.2 3.2 2 0.47 Barium 120 130,000 − 28.5 17.1 77.5J 19.5J 7.2 Chromium 210 470 − 48.7 11.2 66.8 23.7 5.5 Lead 400 1,400 − 647 8.2 324J 88.5J 16

Notes: 1. SCTLs are based on Chapter 62-777, FAC criteria dated 17 April 2005.

2. The Base-Specific Soil Cleanup Goals for PAHs were agreed upon at the 19 September 1996 BCT meeting, based on the findings presented in “A Practical Approach for the Development of Typical Basewide PAH Concentrations Not Related to Waste Handling Practices for Use in Risk Management Decisions,” (Woodward-Clyde, 1996).

3. The Base-Specific Soil Cleanup Goal for arsenic is based on the Arsenic Background Study completed in November 1996 (AFBCA, 1996). 4. Sample Type: SS = surface soil sample. SB = soil boring. 5. bgs = below ground surface. 6. Units: µg/kg = micrograms per kilogram; mg/kg = milligrams per kilogram. 7. PAHs were calculated as the sum of the benzo(a)pyrene equivalents for the carcinogenic PAHs. 8. Bold text denotes results that exceed the residential SCTL. 9. Dark shaded cells denote results that exceed the commercial/industrial SCTL. 10. ND = Not detected above the method detection limit. 11. Qualifiers: J = The value is estimated. P = The percent difference between the two columns was greater than 25 percent.

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TABLE 2-3 (CONTINUED) OPERABLE UNIT 25 – HUSH HOUSE AREA

CONSTITUENTS IN SOIL EXCEEDING SOIL CLEANUP TARGET LEVELS (SCTLs) 1996 SITE INVESTIGATION (WOODWARD-CLYDE, 1997)

SCTL1

Constituent Residential Commercial/

Industrial

Base-Specific Soil Cleanup

Goals2,3

SB-0005-04 0 ft bgs5

29-Jan-96

SB-0006-0 0 ft bgs

29-Jan-96

SB-0007-0 0 ft bgs

29-Jan-96

SB-0007-2 2 ft bgs

29-Jan-96

SB-0008-0 0 ft bgs

29-Jan-96 Polycyclic Aromatic Hydrocarbons (µg/kg)6

PAHs7 100 700 − 10 1888 7599 ND 389 Benzo(a)anthracene − − − ND10 96J11 380J ND 190J Benzo(a)pyrene 100 700 1,500 ND 130J 430J ND 190J Benzo(b)fluoranthene − − − 50 230J 630 ND 370J Benzo(k)fluoranthene − − − 47 140J 460J ND 190J Chrysene − − − ND 170J 510 ND 240J Dibenz(a,h) anthracene − − 1,500 ND ND 140J ND 100J Indeno(1,2,3-cd)pyrene − − − ND 110J 410J ND 240J

Napthalene 2,000 2,800 − ND ND ND ND ND Organochlorine Pesticides (µg/kg)

PCB (Arochlor Mixture) 500 2,600 − ND 58 192 ND 74 Inorganics (mg/kg)6

Antimony 27 370 − ND ND 17.9J ND ND Arsenic 2.1 12 10 6.6 10.6 21.5 3.2 3.0 Barium 120 130,000 − 10.7 19.8J 75.3J 8 21J Chromium 210 470 − 60.2 28.7 28.6 15.6 23.5 Lead 400 1,400 − 247 93.1J 138J 3.9 497J

Notes: 1. SCTLs are based on Chapter 62-777, FAC criteria dated 17 April 2005.

2. The Base-Specific Soil Cleanup Goals for PAHs were agreed upon at the 19 September 1996 BCT meeting, based on the findings presented in “A Practical Approach for the Development of Typical Basewide PAH Concentrations Not Related to Waste Handling Practices for Use in Risk Management Decisions,” (Woodward-Clyde, 1996).

3. The Base-Specific Soil Cleanup Goal for arsenic is based on the Arsenic Background Study completed in November 1996 (AFBCA, 1996). 4. Sample Type: SB = soil boring. 5. bgs = below ground surface. 6. Units: µg/kg = micrograms per kilogram; mg/kg = milligrams per kilogram. 7. PAHs were calculated as the sum of the benzo(a)pyrene equivalents for the carcinogenic PAHs. 8. Bold text denotes results that exceed the residential SCTL. 9. Dark shaded cells denote results that exceed the commercial/industrial SCTL. 10. ND = Not detected above the method detection limit. 11. Qualifiers: J = The value is estimated.

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Ground-water samples also were collected from the two monitoring wells in 1997, 1998, and 2001. Ground-water samples collected from the monitoring wells in 1994–1998 were analyzed for VOCs, SVOCs, organochlorine pesticides, PCBs, and metals. Samples collected in 2001 were analyzed only for VOCs and metals. Low concentrations of VOCs, SVOCs, and metals were detected during the investigations in 1994 and 1996 (Woodward-Clyde, 1997). Ground-water monitoring conducted in 1997, 1998, and 2001 continued to indicate the presence of low concentrations of some target constituents in ground water; however, the last round of sampling performed in 2001 showed isopropylbenzene, also referred to as cumene, as the only constituent exceeding ground-water cleanup target levels (GCTLs). Table 2-4 summarizes ground-water results that exceed current GCTLs. During the 2001 monitoring event, isopropylbenzene was detected at monitoring well MW2 at 2.4 micrograms per liter (µg/L). The GCTL for isopropylbenzene is 0.8 µg/L and is based on organoleptic criteria. This constituent does not have a primary or secondary drinking water standard. 2-methylnaphthalene was detected at a concentration of 6.9 µg/L in monitoring well MW2 in 1998; however, no GCTL had been developed for 2-methylnaphthalene in 1998. In 1999, the GCTL for 2-methylnaphthalene was established in FAC 62-777 at 20 µg/L. Because the detected concentration of 2-methylnaphthalene did not exceed the GCTL established in 1999, SVOC analyses were not performed on samples collected during the 2001 ground-water sampling event. In 2004, the GCTL for 2-methylnaphthalene was increased to 28 µg/L. Concentrations of 2-methylnaphthalene do not exceed the GCTL.

2.5.2 Contaminant Fate and Transport.

PAHs, naphthalene, PCBs, arsenic, barium, antimony, and lead remain at concentrations exceeding unrestricted use and unlimited exposure criteria, represented by the residential SCTLs, in soil at OU-25. PAHs and naphthalene are generally stable in the environment due to the stability of their aromatic ring structure. They will slowly degrade over time, but will likely persist in soil at the site for many years. They are relatively immobile in soil and significant source material is not present. Therefore, they are not expected to pose a risk to contaminate underlying ground water. In addition, the absence of significant concentrations of these contaminants in ground water further supports the conclusion that PAHs and naphthalene contamination are unlikely to pose a risk to contaminate underlying ground water.

Concentrations of antimony, arsenic, barium, and lead exceeding residential SCTLs remain in soil at isolated sample locations. They are generally stable in the environment and will not degrade significantly over time. Given the relatively low concentration, small quantity present at the site, and lack of source material, it is not expected to pose a risk to contaminate underlying ground water. In addition, the absence of significant concentrations of these contaminants in ground water further supports the conclusion that metals contamination are unlikely to pose a risk to contaminate underlying ground water.

A small amount of PCB-contaminated soil remains at OU-25. Similar to PAHs, PCBs are generally stable in the environment, and will likely remain in soils at the site for many years. They are relatively immobile in soil and are not expected to pose a risk to contaminate underlying ground water. This is supported by ground-water sampling and analysis conducted in 1994−2001 where PCBs were not detected in ground water. Given their low concentration

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TABLE 2-4

OPERABLE UNIT 25 – HUSH HOUSE AREA CONSTITUENTS IN GROUND WATER EXCEEDING GROUND-WATER CLEANUP TARGET LEVELS (GCTLs)

GROUND-WATER MONITORING RESULTS (VERSAR, 1998; IT CORPORATION, 2001)

Constituent GCTL1 MW2

24-Jul-97 MW2

15-Jan-98 MW2

18-Jul-01 Volatile Organics (µg/L)2

Isopropylbenzene (cumene) 0.83 7.04 11.0 2.4

Notes: 1. GCTLs are based on Chapter 62-777, FAC criteria dated 17 April 2005. 2. Units: µg/L = micrograms per liter. 3. The GCTL for isopropylbenzene is not an enforceable National Primary Drinking Water Standard under the Safe Drinking Water Act. Instead, the GCTL is a non-

enforceable secondary standard based on organoleptic criteria, which represent concentrations that would impart an unpleasant taste or odor to the ground water rather than levels that would pose a potential health risk.

4. Bold text denotes results that exceed the GCTL.

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and absence of source material in soil at the site, it is not expected to pose a risk to contaminate underlying ground water.

2.6 Current and Potential Future Land and Resource Uses

Land use within the boundary of Homestead ARB includes active flight operations, “industrial” shops that support flying missions of the AFRC, and Homestead ARB temporary housing units. However, the OU-25 property has not been actively used since 1992. Aircraft engine testing was discontinued at the site in the mid-1980s, when the Hush Houses were constructed for this purpose and began operation. Waste storage at the site was temporary and was discontinued a short time after hurricane Andrew in 1992. Neither the site nor the underlying ground water are currently used for any purpose, and access to the site is strictly controlled due to its presence on an active AFRC installation, in close proximity to the flightline. Currently exposed populations associated with OU-25 include commercial/industrial workers such as grounds maintenance workers who occasionally mow the grass in the areas surrounding the pad. No other personnel enter the contaminated portions of OU-25 on a regular basis. Although highly unlikely, hypothetical future exposed populations could include construction workers and on-site residents.

Homestead ARB is expected to remain an active Air Force installation for the foreseeable future. As such, access to the installation will continue to be strictly controlled and limited to authorized individuals. Furthermore, active flight operations are anticipated to continue on the runway adjacent to OU-25, which will continue to act as a barrier between the site and the main portion of the installation and significantly limit access to or construction on the OU-25 property. Use of the OU-25 property is expected to remain limited and commercial/industrial in nature, with the most likely exposure to grounds maintenance workers that occasionally mow the grass at the site. There are no plans to further develop or utilize the property or the underlying ground water.

The surficial (i.e., uppermost) aquifer, the Biscayne Aquifer, is the sole source of potable water in Miami-Dade County and has been declared a sole-source aquifer by the EPA, pursuant to Section 1425 of the Federal Safe Drinking Water Act. Ground water is not currently used in the OU-25 area. In addition, there no longer are any active drinking-water wells located within Homestead ARB, and no new potable or non-potable water wells are planned for this area.

2.7 Summary of Site Risks

A streamlined risk evaluation was conducted as part of the FS for OU-25. The following discussion provides a summary of the evaluation of the potential risks posed by OU-25 to human health and the environment. FDEP’s SCTLs and ground-water cleanup target levels (GCTLs) and the MCLs were used as initial screening levels to conservatively evaluate if additional risk evaluation was necessary. In general, the steps in the risk evaluation process were as follows:

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1) Maximum concentrations of each contaminant detected in soil and ground water were compared with FDEP’s residential SCTLs or GCTLs, which are based on cancer target risk levels of 1 x 10-6 or non-cancer hazard indices of 1.0, and EPA’s MCLs, respectively.

2) Contaminants in soil and ground water whose maximum concentrations did not exceed the residential SCTLs, GCTLs, or MCLs were dropped from further risk evaluation.

3) Exposure Point Concentrations (EPCs), based on the 95% UCL on the mean, were calculated in accordance with EPA guidance for contaminants whose maximum concentrations exceeded residential SCTLs, GCTLs, and/or MCLs.

4) The calculated EPCs were compared with the commercial/industrial SCTLs, which also are based on cancer target risk levels of 1 x 10-6 or non-cancer hazard indices of 1.0, and MCLs to identify contaminants requiring further risk evaluation.

5) If all EPCs were less than the commercial/industrial SCTLs, GCTLs, or MCLs, the risk evaluation was not continued.

6) Estimated cancer risks and non-cancer hazards were calculated for contaminants whose EPCs exceeded the commercial/industrial SCTLs and/or MCLs (i.e., the COCs) using standard EPA risk assessment methodology.

7) Estimated cancer risks and non-cancer hazards were compared to EPA’s target cancer risk range of 10-4 to 10-6 and non-cancer hazard index of 1.0.

Overall, the results of the OU-25 risk evaluation indicate that contaminated soil does not pose an unacceptable risk to current and anticipated future users of the site (i.e., commercial/industrial workers) because the risk for commercial/industrial workers was less than 1 x 10-4 and the hazard index was less than 1.0. The risk evaluation also indicated that exposure to OU-25 soil by a hypothetical future construction worker or resident may pose an unacceptable risk and/or hazard. Additional details regarding land use, exposure assumptions, exposure point concentrations (EPCs), toxicity assessment, and risk characterization are provided below.

2.7.1 Summary of Human Health Risk Assessment

A focused human health risk evaluation was conducted as part of the Streamlined FS for OU-25.

Identification of Contaminants of Concern – Following an initial comparison of contaminant concentrations in OU-25 soil with FDEP residential SCTLs and in OU-25 ground water with FDEP GCTLs and EPA MCLs, it was determined that PAHs (i.e., benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-cd)pyrene), PCBs, naphthalene, antimony, arsenic, barium, and lead required additional consideration in the streamlined risk evaluation. Table 2-5 provides summary information for each COC identified at OU-25, including: frequency of detection; minimum and maximum detected concentrations; and the 95% upper confidence limit (UCL) of the mean. EPCs for COCs were calculated as the 95% UCL on the mean using EPA’s ProUCL software. The EPC for arsenic exceeded the residential SCTL but was less than the base-specific background concentration of 10 mg/kg. As a result, remedial action is not necessary to address arsenic in soil at OU-25.

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No constituents in ground water exceeded the MCLs, so further risk evaluation was not required. Isopropylbenzene was the only contaminant of concern present in ground water at a concentration greater than its FDEP GCTL. It should be noted that this constituent does not have a primary or secondary drinking water standard (i.e., MCL or Maximum Contaminant Level Goal). In addition, the GCTL for isopropylbenzene is based on organoleptic criteria, which means that the contamination would impart an unpleasant taste and/or odor to the water, rather than pose a significant potential health risk if it were consumed as a drinking water source. Given the isolated occurrence of isopropylbenzene in only one monitoring well and the relatively low concentrations, isopropylbenzene in ground water is unlikely to pose a significant risk to future users of the site. As a result, exposure to isopropylbenzene in ground water was not considered to pose a significant risk to current or future users of the site and was eliminated from the risk evaluation.

Table 2-5 Summary Information for Constituents of Concern in Soil

Exceeding the FDEP Soil Cleanup Target Levels

COCs Units1

Detected Concentration

Range

Frequency of

Detection

FDEP Commercial/

Industrial SCTL2 EPC3

Upper Confidence

Limit Method

Total PAHs µg/kg 175–5,4744 – 700 3,417.8 95% Chebyshev

(Non-Parametric)

Benzo(a)pyrene µg/kg 130–4,100 11/21 700 1,859.7 99% Chebyshev

(Non-Parametric)Benzo(a)anthracene µg/kg 96–3,300 10/21 – – – Chrysene µg/kg 66–4,100 11/21 – – – Benzo(b)fluoranthene µg/kg 50–4,900 12/21 – – – Benzo(k)fluoranthene µg/kg 42–3,800 13/21 – – – Indeno(1,2,3-cd)perylene µg/kg 110–2,800 11/21 – – – Dibenz(a,h)anthracene µg/kg 43–460 7/21 – – –

PCB Mixture5 µg/kg 58–1,523 8/21 2,600 423.3 95% Chebyshev

(MVUE)

Naphthalene µg/kg 74–5,600 4/21 300,000 1,775.4 95% Chebyshev

(Non-Parametric)Antimony mg/kg 4.3–27.4 8/21 370 12.51 95% H-UCL

Arsenic mg/kg 0.43–21.5 19/21 12 9.4 95%

Approximate Gamma UCL

Barium mg/kg 4.4–129 21/21 130,000 61.93 95% Chebyshev

(Non-Parametric)

Lead mg/kg 0.45–647 27/27 1,400 266.4 95% Adjusted Gamma UCL

1. Units: µg/kg = micrograms per kilogram; mg/kg = milligrams per kilogram. 2 FDEP SCTLs are based on Chapter 62-777, FAC criteria dated 17 April 2005 3. Exposure point concentrations (EPCs) were calculated for PAHs as the sum of the benzo(a)pyrene toxicity equivalents for the

carcinogenic PAHs where half the detection limit was used for non-detected data. 4. Total PAH detections are based on the sum of the benzo(a)pyrene toxicity equivalents for all carcinogenic PAHs. 5. PCB Mixtures represent the sum of all PCB congeners detected in a given sample including Aroclor-1232, Aroclor-1248, and

Aroclor-1260.

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Exposure Pathway and Receptor Analysis - Based on an evaluation of the current and reasonably anticipated future use, the population group identified as current and future potentially exposed receptors at OU-25 are commercial/industrial workers such as a grounds maintenance worker mowing the grass. Although unlikely given the site location, a construction worker receptor could also be exposed to contaminated soil in the unlikely event that construction activities occur on the OU-25 site. Finally, while not warranted based on reasonably anticipated future land use, a residential receptor was evaluated as a means to evaluate an unrestricted use and unlimited exposure scenario, which is consistent with current EPA and Air Force risk assessment and remedy selection policy. Potentially complete exposure pathways for commercial/industrial workers and construction workers exposed to the site include inhalation of fugitive dust and incidental ingestion of and direct contact (i.e., dermal exposure) with impacted surface and subsurface soil. Residential receptors were assumed to include inhalation of fugitive dust and incidental ingestion of and direct contact (i.e., dermal exposure) with impacted surface and subsurface soil. Residential receptors are typically not assumed to be exposed to subsurface soil. However, because of the shallow depth to bedrock at OU-25 (i.e., generally less than 5 ft bgs) and in an effort to conservatively estimate risk, residential exposure to subsurface soil was assumed to be a complete exposure pathway.

Exposure Point Concentrations –EPCs represent a conservative estimate of the concentration of COCs within the defined exposure point, which is the OU-25 area. Consistent with EPA guidance (EPA, 2002), the 95 % upper confidence limit of the mean (95% UCL) was calculated as a conservative estimate of the reasonable maximum exposure (RME) concentrations to which a receptor could potentially be exposed. The 95% UCLs for COCs were calculated using EPA software (ProUCL, Version 3.0) and are presented in Table 2-5. Where a COC was not detected, one-half of the laboratory detection limit was used as an estimate of the non-detected concentration. EPCs were calculated for PAHs as the sum of the benzo(a)pyrene toxicity equivalents for the carcinogenic PAHs.

Exposure Assumptions – To evaluate risks associated with exposure to COCs at OU-25, receptor-specific exposure assumptions for human receptors identified as potentially exposed receptors at OU-25 are presented in Table 2-6. With one exception, RME assumptions were used for all receptors and were based on default values provided in various EPA guidance documents such as EPA’s Risk Assessment Guidance for Superfund: Volume 1, Human Health Exposure Manual, Part A (RAGS) (EPA, 1989), Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites (SSL Guidance) (EPA, 2002), and the Region 9 Preliminary Remediation Goals (PRGs) Users’ Guide and Background Technical Document (EPA Region 9, 2004). The single exception was for the exposure frequency assumption for a construction worker. Because of the location of the site adjacent to the runway and the small size of the site, it is highly unlikely that a large-scale construction project, requiring 250 days to complete, would occur at OU-25. It is much more realistic to assume that any construction activities that would occur at OU-25 in the future would involve smaller-scale activities, which are likely to require significantly less than 100 days to complete. As a result, a site-specific exposure frequency of 100 days per year was assumed for a construction worker instead of the default value of 250 days per year. All other exposure assumptions selected for all receptors were default values. These exposure parameters and the EPCs for each COC were used to calculate intake values for residential receptors and commercial/industrial and construction workers based on the standard intake equations for ingestion and dermal contact provided in EPA’s

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RAGS. Intake due to inhalation of fugitive dust was estimated using the intake equations provided in EPA’s SSL guidance. To estimate carcinogenic risk and noncarcinogenic hazard associated with exposure to COCs, intake estimates are combined with toxicity data.

Toxicity Assessment – With the exception of lead, the cancer slope factors (CSFs) and reference dose (RfD) values used in this risk evaluation were the most current data for COCs published in EPA’s Integrated Risk Information System.

EPA does not currently provide RfDs for lead because a threshold level below which toxic effects are not observed has not been established. Consequently, noncarcinogenic hazard associated with exposure to lead by residents and by commercial/industrial and construction workers were evaluated conservatively based on a comparison with the EPA Region 9 PRGs for residential and commercial/industrial receptors, respectively.

Table 2-6 Risk Evaluation Exposure Assumptions

Receptor

Exposure Parameters Resident1

(Child/Adult) Commercial/

Industrial Worker Construction

Worker Exposure point concentration EPC Chemical-specific Chemical-specific Chemical-specific Body weight (kg) BW 15/70 70 70 Averaging time (carcinogens) ATc 25,550 25,550 25,550 Averaging time (noncarcinogens) ATnc 2,190/8,760 9,125 365 Particulate emission factor (m3/kg) PEF 1.2E+09 1.2E+09 1.2E+09 Exposure frequency (d/yr) EF 350 250 100 Exposure duration (yr) ED 6/24 25 1 Ingestion rate (mg/day) IR 200/100 100 330 Exposed skin surface area (cm2) SA 2,800/5,700 3,300 3,300 Inhalation rate (m3/day) InhR 10/20 20 20 Adherence factor (mg/cm2) AF 0.2/0.07 0.2 0.3 Fraction from impacted source FI 1.00 1.00 1.00 Conversion factor (kg/mg) CF 1.0E-06 1.0E-06 1.0E-06 Dermal absorption factor DA Chemical-specific2 Chemical-specific2 Chemical-specific2

1. A residential receptor is based on exposure assumptions for a child from 1 to 6 years old and an adult from 7 to 31 years old. Risks are calculated separately for the child and adult residents and then are combined.

2. Dermal Absorption Factors were adopted from the EPA’s Risk Assessment Guidance for Superfund (RAGS), Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) Interim (EPA, 2000).

Risk Characterization – The final step in this risk evaluation involves combining toxicity and intake data to provide quantitative estimates of carcinogenic risk and noncarcinogenic hazard associated with exposure to COCs for each exposure pathway. Using the standard equations for calculating risk and hazard provided in EPA’s RAGS, quantitative estimates of carcinogenic risk and noncarcinogenic hazard were developed for each receptor, which are provided in Table 2-7.

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Table 2-7 Carcinogenic Risk and Noncarcinogenic Hazard Estimates for OU-25

For known or suspected carcinogens, acceptable exposure levels are generally concentration levels that represent an excess upper bound life-time cancer risk to an individual of between 1 x 10-4 and 1 x 10-6 using information on the relationship between dose and response. In addition, EPA risk assessment guidance indicates that acceptable exposure levels for noncarcinogens correspond to a cumulative noncarcinogenic hazard index of less than 1.0. Based on a comparison of the calculated risks and hazards for potentially exposed receptors at OU-25 with acceptable exposure levels as defined EPA and Air Force policy and guidance , contaminated soil does not pose an unacceptable risk to commercial/industrial workers, which are the potentially exposed receptors that are most representative of current or reasonably anticipated future land use. The carcinogenic risk level for the commercial/industrial worker population was less than the upper limit of EPA’s target risk range of 1 x 10-4 and the hazard index was less than 1.0.

The calculated risk for a hypothetical, future construction worker is less than the upper limit of EPA’s target risk range of 1 x 10-4, suggesting that contaminated soil would not pose an unacceptable carcinogenic risk. Noncarcinogenic hazard for a construction worker was estimated to be minimally greater than 1.0; however, as previously stated, because of the location of the OU-25 site near the runway, a construction worker scenario is unlikely. In addition, it should be noted that concentrations of antimony and arsenic that are consistent with background soil levels were included in the noncarcinogenic hazard calculation. If the estimated noncarcinogenic hazard from arsenic and antimony is removed from the cumulative hazard index for the construction worker receptor, the resulting noncarcinogenic hazard (approximately 0.3) is significantly less than 1.0, indicating that a substantial portion of the cumulative hazard index is not site-related.

The carcinogenic risk for a residential receptor, which is representative of an unrestricted use and unlimited exposure scenario, was less than the upper limit of EPA’s target risk range of 1 x 10-4 but greater than the lower limit of 1 x 10-6. Noncarcinogenic hazard for a residential receptor exceeded the 1.0 target threshold. As a result, impacted soil at OU-25 may pose an unacceptable risk to hypothetical residential receptors. Figure 2-2 shows individual sample locations where contaminant concentrations exceeded the FDEP residential SCTLs.

While FDEP indicated they could not agree with the use of the 1 x 10-4 target risk level used in the risk evaluation, it concurred with the overall conclusions of the risk evaluation and agreed that the selected remedy for OU-25 was appropriate. Section 2.10.3 provides additional discussion of FDEP’s rationale for supporting the selected remedy for OU-25. Noncarcinogenic hazards associated with exposure to lead by residents and by commercial/industrial and construction workers are evaluated differently because toxicity

Receptor Risk Hazard Index Resident 8.04 x 10-5 1.5 Commercial/Industrial Worker 2.27 x 10-5 0.1 Construction Worker 6.98 x 10-5 1.1

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information is not available from EPA. As a result, lead was evaluated based on a comparison with the EPA Region 9 PRGs for residential and commercial/industrial receptors, respectively. The EPC for lead (266.4 mg/kg) was significantly less than both the EPA Region 9 residential PRG of 400 and the commercial/industrial PRG of 800 mg/kg. As a result, exposure to lead in soil at OU-25 is not considered to pose an unacceptable noncarcinogenic hazard for commercial/industrial workers or future residents or construction workers.

2.7.2 Summary of Ecological Risk Assessment

No significant ecological risks are anticipated at OU-25 because

• The area of soil contamination is small relative to the home ranges of potential target ecological receptors (i.e., gray fox)

• The site’s proximity to an active runway makes the limited habitat unattractive to many animals (i.e., short-tailed shrew).

The area of soil contamination at OU-25 consists of a narrow band, approximately 25 ft wide, around the outer edge of the concrete pad. Because the contaminated portions of OU-25 are small in comparison to the size of the home ranges of most plants and animals, the potential for significant exposure of wildlife to contaminants is limited. Furthermore, because the grassy areas of OU-25 are regularly mowed and the site is located near an active runway, ground cover that would provide favorable habitat is absent from a significant portion of the site and activities associated with flight operations make the limited habitat at the site unattractive to many animals. Because of the unattractive and limited nature of the ecological habitat offered by OU-25, it is considered highly unlikely that contaminant concentrations associated with the site would pose a significant risk to ecological receptors.

2.8 Remedial Action Objectives

The remedial action objectives (RAOs) will impact the ability of the site to be used for residential use. The RAOs will also impact excavation activities at the site, by requiring that exposure to soil be controlled in such a way as to reduce the risk to an acceptable level. In the event that use of the site changes, the remedy and these RAOs will trigger additional action to prevent unacceptable exposure. These RAOs were selected in response to risks to residents and construction workers discussed in more detail in Section 2.7. The combination of actions proposed in this proposed plan are intended to reduce risk to these receptors such that there is no longer an unacceptable risk. As described in Section 2.7.1, the risk evaluation indicates that carcinogenic risk and noncarcinogenic hazard associated with exposure to OU-25 soil do not pose an unacceptable risk to commercial/industrial workers. Therefore, remedial action is not required based on the current or reasonably anticipated use scenario.

The Remedial Action Objectives (RAOs) for OU-25 are intended to

• Prevent residential exposure to contaminants of concern at concentrations greater than the residential SCTLs identified in Table 2-8.

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• Limit digging in the OU-25 area to ensure that construction workers without appropriate personal protective equipment are not exposed to contaminants of concern at concentrations greater than the commercial/industrial SCTLs identified in Table 2-8.

Table 2-8 Soil Cleanup Target Levels for COCs at OU-25

COCs Units Residential SCTL Commercial/Industrial

SCTL PAHs µg/kg 100 700 Benzo(a)pyrene µg/kg 100 700 Dibenz(a,h)anthracene µg/kg − − Naphthalene µg/kg 2,000 − PCB mixture µg/kg 500 2,600 Antimony mg/kg 27 370 Barium mg/kg 120 130,000 Lead mg/kg 400 1,400

NOTE: PAHs are evaluated as the sum of the benzo(a)pyrene toxicity equivalents for the individual PAHs.

2.9 Description of Alternatives

The Streamlined FS for OU-25 (Booz Allen, 2006) identified three final remedy alternatives for consideration. Based on the site characteristics described in Section 2.5, the current and anticipated future land uses described in Section 2.6, and the potential risks described in Section 2.7.1, the most viable remedial alternatives for OU-25 are:

Alternative 1 – No Further Action Alternative 2 – Land Use Controls Alternative 3 – Excavation and Off-Site Disposal.

Each of these alternatives is described below and was evaluated during the detailed analysis of alternatives in the FS.

2.9.1 Alternative 1 – No Further Action

The no further action alternative would require nothing to be done to change the current contaminated soil conditions at OU-25. No excavation, treatment, or containment of the contaminated soil would be conducted. Unrestricted use of the property and unlimited exposure to contaminated soil would be allowed. While it is likely that contaminant concentrations will reduce over time due to natural degradation processes, the rate of reduction would not be measured.

The NCP, 40 CFR 300.430(e)(6), requires that a no action alternative (or in cases where a previous removal action has been conducted, a no further action alternative) be developed and included in the analysis of alternatives. The no further action alternative is used as a baseline to compare other alternatives.

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2.9.2 Alternative 2 – Land Use Controls

Alternative 2 would include LUCs being implemented to prohibit current and future users of the site from using the property for residential purposes, hospitals for human care, public or private schools, or day care centers for persons under 18 years of age. In addition, digging restrictions would be implemented to ensure that construction workers are not exposed to contaminants in soil. Alternative 2 would also include LUCs requiring that any contaminated soil that is excavated at OU-25 will be properly managed on site and that any contaminated soil transported off site will be managed in accordance with applicable RCRA regulations. Lastly, digging restrictions would be implemented to ensure that construction workers are not exposed to unacceptable concentrations of contaminants in soil. Use restrictions would be specified in the BGP and implemented, monitored, maintained, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personnel.

2.9.3 Alternative 3 – Excavation and Off-Site Disposal

Alternative 3 requires contaminated surface soil to be excavated, removed from the site, and disposed of at an appropriately permitted landfill. LUCs would be implemented temporarily to minimize contact with the contaminated soil prior to completion of excavation activities. Soil exceeding the residential SCTLs would be excavated using a backhoe, staged on site in covered piles or roll-off boxes pending waste characterization, and transported to an off-site disposal facility for final disposition. If successfully implemented, all contaminated soil would be removed from the site, so long-term implementation of LUCs would not be required. The estimated volume of soil that will require excavation and off-site disposal is approximately 815 cubic yards.

2.10 Summary of Comparative Analysis of Alternatives

During the detailed analysis of alternatives conducted in the FS, each of the three potential remedial alternatives was evaluated against seven of the nine criteria specified in the NCP. The first two criteria are threshold criteria. These are statutory requirements that the alternative must satisfy to be considered a viable final remedy option.

1. Overall protection of human health and the environment 2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs).

Appendix C in the FS provides a comprehensive evaluation of chemical-, location-, and action-specific ARARs.

The next five criteria are known as the primary balancing criteria. These are the technical criteria upon which the detailed analysis is based.

3. Long-term effectiveness and permanence 4. Reduction of toxicity, mobility, and volume through treatment 5. Short-term effectiveness 6. Implementability

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7. Cost.

The following two criteria, known as the modifying criteria, also were evaluated; however, they were not evaluated as part of the FS. These criteria were assessed following regulatory and public review of the FS and Proposed Plan.

8. State acceptance 9. Community acceptance.

A detailed evaluation of each of the three remedial alternatives described in Section 2.9 was conducted in the FS. The comparative analysis from the FS, which describes the relative benefits and deficiencies of each alternative, is summarized below.

2.10.1 Threshold Criteria

All remedial action alternatives must be protective of human health and the environment and comply with ARARs in order to be considered acceptable for selection as the preferred alternative. Both Alternative 2, the selected alternative, and Alternative 3 satisfy the threshold criteria, as described below. Therefore, either Alternative 2 or 3 would be an acceptable final remedy for OU-25. Alternative 1 – No Further Action is not protective of the unrestricted use and unlimited exposure scenario. As such, it is not a viable option for the final remedy at OU-25.

Overall Protection of Human Health and the Environment

As described in Section 2.7.1, COCs were not identified at OU-25 at concentrations that would pose a risk under a commercial/industrial use scenario, which is the current and reasonably anticipated future use scenario. Therefore, Alternative 1 – No Further Action would be protective of human health and the environment under the current and anticipated future use scenario. However, Alternative 1 does not include LUCs required to be protective of the unrestricted use and unlimited exposure scenario. Alternative 2 would protect human health and the environment by preventing unacceptable exposure to contaminated soil at the site through the implementation of LUCs. Alternative 3 would protect human health and the environment through removal of the soil contamination from the site.

Compliance with ARARs

Alternatives 2 and 3 would comply with ARARs, including, but not limited to, Chapters 62-777 and 62-780 of the FAC. In addition, as discussed in Section 2.7.1, OU-25 soil does not pose a significant risk to commercial/industrial workers. Therefore, Alternative 1 would comply with these ARARs because the risk evaluation indicates that contaminant concentrations in soil do not pose a risk to commercial/industrial workers, indicating that no further action is required to comply with these ARARs.

In order to evaluate the need for LUCs, risk and hazard estimates were developed for residential and construction worker receptors. Based on the risk evaluation discussed in Section 2.7.1, potentially unacceptable risks and/or hazards were identified for hypothetical future construction workers and on-site residents, indicating a need for LUCs. Alternative 1 would

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not include LUCs necessary to be protective of the unrestricted use/unlimited exposure scenario or to prevent exposure by future construction workers. Alternative 2 complies with these requirements by instituting LUCs to prevent unacceptable exposure to soil containing contaminant concentrations greater than the residential SCTLs. Alternative 3 complies with these requirements by removing soil that contains contaminant concentrations greater than the residential SCTLs so that LUCs are no longer required. A more comprehensive evaluation of chemical-, location-, and action-specific ARARs is provided in Appendix C of the FS.

2.10.2 Balancing Criteria

Each of the three alternatives were further evaluated using the balancing criteria described in the NCP. The results of that evaluation are summarized below for Alternatives 2 and 3. Alternative 1 has been excluded from the summary below because it was eliminated from further consideration due to the lack of LUCs required to be protective of the unrestricted use and unlimited exposure scenario. The selected alternative, Alternative 2, was selected based on the overall ability of the alternative to satisfy these criteria.

Long-Term Effectiveness and Permanence

Both Alternative 2 and Alternative 3 would provide adequate long-term effectiveness. Alternative 2 would remain effective over the long term through ongoing imposition of use restrictions and an established monitoring and enforcement program operated by the AFRC. Alternative 3 may provide the greatest long-term effectiveness if all soil contamination can be removed from the site. However, the presence of existing site features, such as concrete pads, may result in incomplete removal of soil contamination, in which case LUCs would ultimately be required.

Reduction of Toxicity, Mobility, and Volume Through Treatment

Neither Alternative 2 nor Alternative 3 would satisfy the statutory preference for treatment. Alternative 2 would leave contamination in place and Alternative 3 would move contamination to a disposal facility. Neither alternative would treat the soil to reduce the toxicity, mobility, or volume of contamination.

Short-Term Effectiveness

Both Alternative 2 and Alternative 3 would provide adequate short-term effectiveness. Alternative 2 would provide immediate protection of human health by imposition of use restrictions, and Alternative 3 would provide short-term protection of human health immediately by imposition of use restrictions and through excavation and removal of contamination from the site within one year. It is intuitively reasonable to assume that excavation of contaminated soil conducted as part of Alternative 3 would increase the potential for exposure to contamination. Soil currently located below-grade and inaccessible to receptors at the site would be exposed where direct contact and/or airborne dispersion would be more likely, although no data have been collected to support this conclusion. Therefore, Alternative 3 would be slightly less effective in the short term because the potential for exposure would be increased during excavation.

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Implementability

Alternative 2 would be more easily implemented than Alternative 3. LUCs would be implemented, monitored, maintained, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personnel at the installation so they would be easily implemented. Alternative 3 would require a significantly higher level of effort and additional complexity to implement. Extensive budget programming, contracting, and planning steps would be required prior to implementation, and completion of the action would require mobilization of staff and heavy equipment to the site; excavation, transportation, and disposal of contaminated soil; and confirmation sampling and sample analysis. In addition, full implementation of Alternative 3 may be hindered by the presence of the concrete pad that could limit the quantity of contaminated soil that can be effectively excavated.

Cost

The estimated cost for Alternative 2 of $49,665 is significantly lower than the estimated cost for Alternative 3, which is $304,282. The difference in cost is primarily attributable to the cost of excavation of contaminated soil in Alternative 3. Since it is uncertain whether all contaminants could be removed through excavation to reduce the potential risk to residential use levels, the return on the additional investment required by Alternative 3 would be questionable. Furthermore, the cost of implementing Alternative 2 assumes that an outside contractor would be used to monitor the LUCs. It is anticipated that the LUCs would actually be implemented, monitored, maintained, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personnel, in which case no external contracting costs would be incurred.

2.10.3 Modifying Criteria

The modifying criteria were evaluated based on comments received on the Proposed Plan (Booz Allen, March 2006) and during the public comment period, which was held between 3 April and 3 May 2006.

State Acceptance

FDEP reviewed and provided comments on the investigation and remedy selection documents for OU-25, including the FS, the Proposed Plan, and this ROD. With one exception, the AFRC has responded to each of FDEP’s comments on these documents in an acceptable manner as indicated in correspondence provided in Appendix B.

FDEP indicated that they could not support the use of a target risk level of 1 x 10-4 because FDEP’s acceptable carcinogenic risk limit is 1 x 10-6. However, FDEP conducted their own independent technical evaluation of the OU-25 data and their findings and conclusions, as stated in their July 13, 2006 letter, are presented below.

“FDEP’s acceptable carcinogenic and noncarcinogenic risk are 1 x 10-6 and a hazard index of 1.0, respectively. Based upon a comparison of contaminant concentrations in the Site Investigation conducted at Operable Unit 25 with Homestead Air Force Based-

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specific background concentrations and industrial/commercial SCTLs, PAHs, including benzo(a)pyrene, and most metals were removed as contaminants of concern. After a Voluntary Interim Removal Action, only arsenic remained at a few soil sampling locations at a concentration exceeding its industrial/commercial SCTL and background concentration. However, the exposure point concentration calculated for arsenic shown in Table 1-1 indicates that it is less than the Department’s industrial/commercial SCTL. This indicates that risks from arsenic in soil at Operable Unit 25 do not exceed the Department’s carcinogenic risk level of 1 x 10-6 under an industrial/commercial use scenario. Based on this, the Department has agreed that a nonresidential land use control and digging restrictions would be an acceptable remedy for Operable Unit 25.”

FDEP also noted in a letter dated September 8, 2006, that the calculated EPC for arsenic in OU-25 soil was less than the accepted Homestead Air Force Base-specific background concentration of 10 mg/kg.

Community Acceptance

Notices were published in the South Dade News Leader on Friday, 31 March 2006, and in The Miami Herald on Thursday, 30 March 2006, to notify members of the public of the opportunity to provide comment on the Proposed Plan for OU-25. The public notices also indicated that a meeting would be held on 20 April 2006, at 7:00 p.m., to discuss the preferred remedial alternatives for OU-25.

Prior to initiation of the public comment period on 3 April 2006, a copy of the Proposed Plan for OU-25 and other historical documents, such as the FS, were made available for public review at the Homestead Branch of the Miami-Dade County Library located at 700 N. Homestead Boulevard in Homestead, Florida.

A public meeting was held on 20 April 2006, from 7:00 to 8:00 p.m., at the City Council Chamber Room in City Hall, located at 790 Homestead Boulevard, Homestead, Florida, to inform members of the public of the preferred remedial alternatives to address contamination at OU-25. A poster presentation was prepared that summarized the information provided in the Proposed Plan and identified the preferred remedial alternative as LUCs. Representatives of AFRC were available at the meeting to discuss the preferred remedial alternatives and to answer questions. No comments were provided on the Proposed Plan or Preferred Alternative during the public meeting.

As indicated in the notices published in local newspapers, a formal public comment period was conducted from 3 April 2006 to 3 May 2006. Comments on the FS and Proposed Plan were provided by DERM in a letter dated 20 March 2006, which were considered in preparing this ROD. No other public comments were received for OU-25 during the public comment period. DERM also provided comments on the Draft Final version of this ROD in a letter dated 28 July 2006, which were considered in preparing this ROD. Responses to DERM’s comments on the Draft Final ROD are provided in Section 3.0, Responsiveness Summary.

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2.10.4 Comparison of Alternatives

Table 2-9 provides a side-by-side comparison of the seven threshold and primary balancing criteria for the three alternatives.

Table 2-9 Comparison of Alternatives

Criteria

Alternative 1 No Further

Action

Alternative 2 Land Use Controls

Alternative 3 Excavation and

Off-Site Disposal Threshold Criteria 1. Overall Protection of Human

Health and the Environment 3 4 4

2. Compliance with ARARs 3 4 4

Primary Balancing Criteria 3. Long-Term Effectiveness and

Permanence 3 3 4

4. Reduction of Toxicity, Mobility, or Volume Through Treatment

0 0 0

5. Short-Term Effectiveness 4 4 3

6. Implementability 4 4 3

7. Cost 4 4 2 0 = Poor; 1 = Fair; 2 = Moderate; 3 = Good; 4 = Excellent

As the table indicates, Alternative 2 – LUCs, and Alternative 3 – Excavation and Off-Site Disposal, both satisfy the threshold criteria of protection of human health and the environment and compliance with ARARs. Therefore, either Alternative 2 or 3 would be an acceptable final remedy for OU-25. Moreover, Alternative 1 does not include LUCs required to be protective of the unrestricted use and unlimited exposure scenario. As such, it is not a viable option for the final remedy at OU-25.

Alternatives 2 and 3 would provide adequate short- and long-term effectiveness and provide immediate protection of human health by imposition of use restrictions. Alternative 2 would remain effective over the long term through ongoing imposition of use restrictions and an established monitoring and enforcement program operated by Homestead ARB Environmental Flight Office personnel. Future use of the OU-25 area for residential use would be restricted. These restrictions would be implemented to prohibit current and potential future users of the site from using the property for residential purposes, hospitals for human care, public or private schools, or day care centers for persons under 18 years of age. Alternative 3 may provide the greatest long-term effectiveness if all soil contamination can be removed from the site. However, soil contamination would be disturbed during remedy implementation so that there would be a short-term increase in the potential for exposure to contaminants. In addition, the presence of existing site features, such as concrete pads, may result in incomplete removal of soil contamination, in which case LUCs would ultimately be required. Neither Alternative 2 nor Alternative 3 would satisfy the statutory preference for treatment. Alternative 2 would leave contamination in place and Alternative 3 would move contamination to a disposal facility.

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Neither alternative would treat the soil to reduce the toxicity, mobility, or volume of contamination.

Alternative 2 would be more easily implemented and less costly than Alternative 3. LUCs would be implemented, monitored, maintained, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personnel so they would be easily implemented and would not incur costs for external contractor support. Excavation and off-site disposal would cost approximately $304,282, and full implementation of the remedy may be hindered by the presence of existing site features such as concrete pads.

2.11 Principal Threat Wastes

The NCP states that EPA expects to use treatment to address the principal threats posed by a site, wherever practicable. This preference does not impact the decision at OU-25 because there are no principal threat wastes present at the site.

Principal threat wastes are defined as those source materials considered to be highly toxic or highly mobile that generally cannot be reliably contained or would present a significant risk to human health or the environment should exposure occur. The contamination present at OU-25 is not considered a principal threat waste because:

They are not highly toxic – Contaminants are present at concentrations that are not significantly greater than the SCTLs and would present an excess cancer risk near the acceptable risk range were exposure to occur.

They are not highly mobile – The concentrations and solubility of the soil contaminants are relatively low, so they are not a potentially significant source of ground water, air or surface water contamination. This observations is supported by ground-water monitoring results that demonstrate that, in the absence of any controls, soil contaminants are not present in the shallow ground water beneath the site.

As a result, aggressive source removal, treatment, or physical containment is not necessary.

2.12 Selected Remedy

To achieve the RAOs defined in Section 2.8, Alternative 2, Land Use Controls, was selected by AFRC as the final remedy for OU-25. Alternative 2 requires that LUCs be placed on the portions of the OU-25 site containing residual soil contamination that exceed unrestricted use and unlimited exposure criteria represented by the residential SCTLs, as specified in Table 2-8. Alternative 2 includes:

• Use Restrictions – Residential use will be prohibited on portions of the OU-25 property containing contaminated soil at concentrations greater than unrestricted use and unlimited exposure criteria represented by the residential SCTLs shown in Table 2-8. The residential use restrictions will be implemented to prohibit property users from

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using the property for residential purposes, hospitals for human care, public or private schools or day care centers for persons under 18 years of age. Use restrictions will ensure that the future land use of the property remains commercial/industrial and does not change to residential use. Figure 2-2 identifies the estimated extent of soil containing contaminant concentrations exceeding residential SCTLs, which will require LUCs to prevent residential use.

• Digging Restrictions – Excavation of OU-25 soil containing concentrations of contaminants greater than the industrial SCTLs shown in Table 1-1 will be managed to ensure that unacceptable exposure to the contaminants does not occur. These restrictions will be enforced through the dig permit system and construction review process that is currently in place throughout Homestead ARB. No construction or digging is allowed without prior approval by the Base Civil Engineer in the form of a dig permit or other approval as required by applicable Air Force instruction (AFI) and procedures. The Base Civil Engineer will not approve dig permits for activities inconsistent with LUCs. The OU-25 LUC boundary on Figure 2-2 identifies the area where digging activities will be restricted.

• Contaminated Soil Management Restrictions – LUCs will be implemented to require that any contaminated soil that is excavated at OU-25 will be properly managed on site and that any contaminated soil transported off site will be managed in accordance with applicable RCRA regulations.

LUCs will allow the property to continue to be used in the current manner and will allow future development of the property for commercial/industrial purposes, as long as contaminated soil is properly managed. Residential use restrictions will ensure that the property is not redeveloped for residential use. Digging restrictions will prevent direct contact with contaminated surface and subsurface soils, prevent emissions of contaminant particles entrained on dust, and ensure proper waste management of contaminated soil that is excavated in the future.

LUCs will remain in place until confirmatory sampling data indicate that contaminant concentrations have declined below unrestricted use and unlimited exposure criteria represented by the residential SCTLs in Table 2-8. The Air Force will utilize its Base General Plan (BGP) as an administrative LUC to prevent any use inconsistent with this ROD. Within 60 days after ROD signature, the Air Force will make appropriate changes to the BGP to incorporate use restrictions for the site. This section of the BGP will state,

Residential use, including hospitals for human care, public or private schools or day care centers for persons under 18 years of age, of OU-25 is prohibited. Any requests (for example, through excavation permits, such as AF Form 103, or the construction review process, AFI 32-1001) for residential use or substantial construction (i.e., construction requiring longer than 100 days, which was used as the exposure frequency in the risk evaluation to show that no unacceptable risks were posed to construction workers by exposure to OU-25 soil) will be denied, unless the procedures for proposed land use changes described in OU-25 Record of Decision (ROD), dated September 12, 2006 are followed. These procedures involve no less than 45-day notice to EPA and FDEP in advance of any proposed

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land use changes that are inconsistent with an industrial/commercial use scenario. See the ROD for additional requirements related to monitoring, reporting, and enforcing of the LUCs.

These restrictions will be documented in the BGP along with a listing of the GPS coordinates of the OU-25 site boundary and a detailed map (Figure 2-2) identifying the OU-25 LUC boundary. The BGP is one of the first and primary documents to be reviewed when installation personnel are proposing projects on the installation. The Air Force will consult the BGP before making any land use decisions at OU-25. AFI 32-1021 requires installations to comply with their BGP and ensure that there are no land-use constraints stemming from the Environmental Restoration Program (ERP) that would impact facility siting and construction.

As defined in AFI 23 32-7062, a BGP establishes a systematic framework for decision-making with regard to the development of Air Force installations. It incorporates various Air Force programs such as operational, environmental, urban planning, and others, to identify and assess development alternatives and ensure compliance with applicable federal, state, and local laws, regulations, and policies at Homestead ARB. AFI 32-7062 requires component installations to develop and maintain a BGP as a central repository for information deemed essential for planning and managing the installation’s physical assets, including environmental siting constraints such as LUCs.

The BGP and any additional LUC determined to be necessary will be implemented, monitored, maintained, reported on, and enforced by the Homestead ARB Installation Commander through the Base Civil Engineer’s Environmental Flight Office personal through existing land-use management programs, such as the Base Civil Engineering Work Clearance Form (AF Fm 103) (digging permit) and the construction review process (AFI 36 32-1001). No construction or digging will be allowed without prior approval by the BCE in the form of a dig permit or other approval as required by applicable AFI and procedures. The BCE will not approve dig permits for activities inconsistent with the residential use scenario as described in this ROD. The Air Force will ensure that these or similar equivalent instructions, processes, and or requirements will be complied with for all proposed construction or soil-disturbing activities.

Although AFRC may later transfer these procedural responsibilities to another party by contract, property transfer agreement, or through other means, AFRC will retain ultimate responsibility for remedy integrity. AFRC will exercise this responsibility in accordance with CERCLA and the NCP. LUCs will be removed from the BGP only after concurrence from EPA and FDEP and after confirmatory sampling data have determined that contaminant concentrations in soil have declined to concentrations less than unrestricted use and unlimited exposure criteria represented by the residential SCTLs identified as the RAOs for OU-25 in Table 2-8.

Any activity that is inconsistent with the LUC objectives or use restrictions, or any other action that may interfere with the effectiveness of the LUCs will be addressed by the Air Force as soon as practicable, but in no case will the process be initiated later than 10 days after the Air Force becomes aware of the activity or action. AFRC will notify the EPA and FDEP as soon as practicable, but no later than 10 days after discovery of any activity that is inconsistent with the

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LUC objectives or use restrictions, or any other action that may interfere with the effectiveness of the LUCs. AFRC will notify EPA and FDEP regarding how the activity that is inconsistent with the LUC objectives or use restrictions will be addressed as soon as practicable, but no later than 10 days after sending EPA and FDEP notification of the breach. AFRC will notify EPA and FDEP 45 days in advance of any proposed land use changes that are inconsistent with LUC objectives or the selected remedy.

AFRC will provide notice to EPA and FDEP at least six (6) months prior to any transfer or sale of OU-25 so that EPA and FDEP can be involved in discussions to ensure that appropriate provisions are included in the transfer terms or conveyance documents to maintain effective LUCs. If it is not possible for the facility to notify EPA and FDEP at least six months prior to any transfer or sale, then AFRC will provide notification as soon as possible but no later than 60 days prior to the transfer or sale of OU-25. In addition to the land transfer notice and discussion provisions above, AFRC further agrees to provide EPA and FDEP with similar notice, within the same time frames, as to federal-to-federal transfer of property. In the event the Air Force transfers the property or any portion of it outside Federal ownership, the Air Force will include the restriction against residential use as defined in this ROD in any deed or transfer instrument. AFRC will provide a copy of executed deed or transfer assembly to EPA and FDEP.

AFRC will not modify or terminate LUCs at OU-25, implementation actions, or modify land use without approval by EPA and FDEP. AFRC will seek prior concurrence before any anticipated action that may disrupt the effectiveness of the LUCs or any action that will alter or negate the need for LUCs.

In addition, monitoring of the environmental use restrictions and controls associated with OU-25 will be conducted annually by AFRC. At the next Five-Year Review cycle, the Five-Year Review will make recommendations on the continuation, modification, or elimination of annual reports and LUC monitoring frequency. The intent of the monitoring will be to ensure that the remedy provides adequate protection of human health and the environment while contaminants remain in OU-25 soil at concentrations that exceed unrestricted use and unlimited exposure criteria defined as the residential SCTLs identified in Table 2-8. The monitoring results will be included in a separate report or as a section of another environmental report, if appropriate, and provided to the EPA and FDEP. The annual monitoring reports will be used in preparation of the Five-Year Review to evaluate the effectiveness of the remedy. The Five-Year Review report will be submitted to the regulatory agencies in accordance with the FFA.

The annual monitoring report, submitted to the regulatory agencies by AFRC, will evaluate the status of the LUCs and how any LUC deficiencies or inconsistent uses have been addressed. The annual evaluation will address whether use of the property has conformed with the restrictions and controls described above.

2.13 Statutory Determinations

Based on the information currently available, the selected remedy meets the threshold criteria and provides the best balance of tradeoffs among the other alternatives with respect to the balancing and modifying criteria. Alternative 2 is the selected remedy because it provides protection of human health and compliance with ARARs comparable to Alternative 3, but

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would be more easily implementable and less costly than Alternative 3. The ARARs for OU-25 include the SCTLs from Chapter 62-777 of the FAC, dated 17 April 2005, as specified in Table 2-8. The LUCs identified in the selected remedy will prohibit residential use of the property where contaminant concentrations in soil exceed residential SCTLs and will ensure that contaminated soil excavated from OU-25 is properly managed. A complete evaluation of ARARs applicable to OU-25 is provided in Appendix C of the FS.

As indicated in Section 2.10.2, Alternatives 2 and 3 provide similar long-term effectiveness. Alternative 2 will remain effective over the long term through ongoing imposition of use restrictions and an established monitoring and enforcement program operated by Homestead ARB Environmental Flight Office personnel through existing land-use management programs. Alternative 3 would remove and dispose of soil containing contaminants at concentrations exceeding the residential SCTLs. Neither Alternative reduces the toxicity, mobility, or volume of contaminants in soil at OU-25. Alternative 2 provides somewhat greater short-term protectiveness than Alternative 3 because LUCs are more easily implemented than excavation and disposal. Given that Alternatives 2 and 3 offer the same level of protectiveness and overall effectiveness, Alternative 2 was selected as the final remedy because the associated costs are significantly less than the cost associated with Alternative 3.

Remedial alternatives that utilize permanent solutions or alternative treatment technologies were considered during the initial screening of technologies performed in the Streamlined FS. However, these technologies were not selected for detailed analysis due to the following reasons.

• The risk evaluation indicates that contaminated soil at OU-25 does not pose a significant risk to current and reasonably anticipated future receptors (i.e., commercial/industrial workers). As a result, the level of risk posed by contamination at OU-25 does not warrant aggressive remedial action using expensive treatment technologies when another alternative, such as LUCs, can provide comparable protection at a significantly lower cost.

• Permanent solutions or alternative treatment technologies, such as thermal treatment of soil and in-situ biotreatment of ground water, were considered during the FS stage at other sites within Homestead ARB with similar contamination and exposure scenarios. However, these technologies were not selected because they were not considered to be cost-effective. As a result, these technologies were excluded from the detailed analysis completed during the OU-25 FS because other remedial alternatives provided equal or greater overall effectiveness at a significantly reduced cost.

• While LUCs do not permanently treat contamination, they provide adequate protectiveness and long-term effectiveness when compared with other treatment technologies but do not require off-site disposal.

Therefore, while considering the preference for permanent solutions and alternative treatment technologies and a bias against off-site treatment and disposal, the AFRC has determined that the selected remedy, Alternative 2 – LUCs, offers the best overall performance of the balancing criteria.

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The selected remedy for OU-25 does not satisfy the statutory preference for treatment as a principal element of the remedy for the following reasons:

No principal threat wastes are present for which aggressive removal or treatment is warranted

LUCs provide comparable protection of human health and are more easily implemented They are also more cost-effective because they will achieve the same level of protection of current and future receptors at a significantly reduced cost.

Because this remedy will result in hazardous substances, pollutants, or contaminants remaining on site above levels that allow for unlimited use and unrestricted exposure, a statutory review will be conducted within five years after initiation of remedial action to ensure that the remedy is, or will be, protective of human health and the environment. Five-year reviews will continue until contaminant concentrations in soil have decreased to levels that allow for unlimited use and unrestricted exposure. This requirement is pursuant to CERCLA §121 and the NCP 40 CFR 300.430(f)(4)(ii).

2.14 Documentation of Significant Changes

The Proposed Plan for OU-25 identified Alternative 2 – LUCs as the preferred remedy and was released for public comment prior to the public meeting on 20 April 2006. The Proposed Plan and other historical documents, such as the FS, were made available for public review at the Homestead Branch of the Miami-Dade County Library located at 700 N. Homestead Boulevard in Homestead, Florida. The Proposed Plan identified Alternative 2, LUCs, as the Preferred Alternative for OU-25. No significant changes to the remedy, as originally identified in the Proposed Plan, were necessary or appropriate subsequent to the public comment period.

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3.0 RESPONSIVENESS SUMMARY

As indicated in Section 2.10.3, public notices published in local newspapers solicited public comments on the preferred alternative for OU-25 and announced a public comment period from 3 April 2006 to 3 May 2006. The public notices also indicated that a meeting would be held on 20 April 2006, at 7:00 p.m., to discuss the preferred remedial alternatives for OU-25. No public comments were provided on the Proposed Plan during the public comment period or on the Preferred Alternative during the public meeting.

The Miami-Dade County Department of Environmental Resources Management (DERM) provided comments on the Streamlined FS and the Proposed Plan dated 20 March 2006. These comments were noted during preparation of the final version of this ROD, and revisions were made to address many of DERMs comments. In addition, DERM provided comments on the Draft Final OU-25 ROD in a letter dated 28 July 2006. These comments are addressed below.

Comments from the Miami-Dade County Department of Environmental Resources Management (DERM) on the Draft Final OU-25 ROD

28 July 2006

DERM Comment: The Cleanup Target Levels (CTLs) and procedures stipulated in Chapters 62-777 and 62-780, Florida Administrative Code (FAC) are listed as Applicable or Relevant and Appropriate Requirements (ARARs) in Appendix C of the Final Feasibility Study (FS). Section 4.0 of the Final FS and Section 2.10 of the Draft Final ROD states that compliance with the ARARs is one of the two statutory threshold requirements that must be satisfied in order for a remedy to be considered a viable option. Furthermore, Section 2.13, paragraph 2, of the Draft Final ROD also states that the CTLs in Chapter 62-777, FAC are the primary ARARs. In addition, the Base Cleanup Team (BCT) members have also agreed that these procedures are applicable to the base.

A life-time cancer risk of 1 x 10-6 (i.e 1 in 1 million) is the applicable and acceptable cancer risk in the derivation of the carcinogenic CTLs presented in Chapter 62-777 and 62-780, FAC. Specifically, Rule 62-780.650(1)(d), FAC states “The justification for alternative CTLs shall be based upon site-specific characteristics affecting the site. In establishing the alternative CTLs for groundwater and soil, the following factors shall be used, as applicable: calculations using a lifetime excess cancer risk level of 1.0E-6 and a hazard index of 1 or less…”

Therefore, the risks derived during the Streamlined Risk Assessment exceed those established specifically by the ARARs and by procedures agreed upon by the BCT members and the proposed remedy is not in compliance with the specified threshold criteria (statutory requirement). DERM reiterates that contaminants above industrial and HARB site-specific CTLs (i.e. PAH’s in soil boring locations SS-03, SS-04, and SB-03) and acceptable exposure risks established by the Streamlined Risk Assessment are present in surface soils at the site and that applicable engineering controls in addition to Residential Land Use Controls and dig restrictions are required for this site.

Air Force Response: DERM’s comment is noted. However, it should be noted that both EPA and FDEP have given their approval for the selected remedy for OU-25. As a result, no changes were made to this ROD in response to this comment.

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DERM Comment: The report shall be accurate and consistent throughout when referring to the applicable cleanup target levels for Homestead Air Reserve Base. For example, arsenic (10 mg/kg) has an alternate residential soil cleanup level (SCTL) based on background and the carcinogenic PAHs have an alternate industrial SCTL. Furthermore, federal Maximum Contaminant Levels (MCLs) for groundwater shall also be used appropriately (i.e. not for soil cleanup target level reference). Text and tables shall be corrected or modified as applicable.

Air Force Response: This comment refers primarily to text discussions at the beginning of Section 2.7, which described the steps performed as part of the OU-25 risk evaluation, and at the beginning of Section 2.7.1, which described the results of a screening level comparison of contaminant concentrations detected at OU-25. The ROD in general and, specifically, the text in these sections has been revised to improve consistency and to clarify that SCTLs were used to screen soil data, and GCTLs and MCLs were used to screen ground-water data. Tables were corrected accordingly.

DERM Comment: Section 1.4 [of the Draft Final OU-25 ROD dated June 2006]. Contaminants either exceed applicable cleanup target levels or they do not exceed applicable cleanup target levels. The discussion on the significance or insignificance of an exposure risk based on how much or little a contaminant exceeds the applicable cleanup target level by or on the basis of how “near” it is to an acceptable range is not appropriate when applying the procedures stipulated in item number 1. The terminology is also used throughout the report. Therefore, DERM recommends removal of the subjective terminology.

Air Force Response: The referenced text, which provides the definition of a principal threat waste, was taken directly from EPA’s A Guide to Principal Threat and Low Level Threat Wastes (OSWER 9380.3-06FS) dated November 1991. However, to improve clarity of the discussion in Section 1.4, the text referring to principal threat wastes has been revised as follows:

“The contaminants listed in Table 1-1 are not considered principal threat wastes because they are present at concentrations that are not greatly above the SCTLs; they do not pose an excess cancer risk greater than the acceptable risk range if exposure to the contaminants were to occur; and they are relatively immobile in soil. As a result, aggressive removal and/or treatment of the contamination is not warranted and only limited action is necessary to protect human health.”

DERM Comment: Unless a site-specific risk assessment is conducted to properly evaluate acceptable non “permanent” residential uses, the term “permanent” shall not precede “residential” when referring to the type of use restrictions to be imposed on the site.

Air Force Response: The ROD has been revised as requested.

DERM Comment: DERM appreciates the opportunity to have comments included in the discussion of Section 3.0 of the Draft Final ROD and would also appreciate if a copy of DERM review letters are also included in the appropriate section of the document.

Principal Threat Wastes are source materials (e.g., contaminated soil or ground

water) that contain highly toxic or highly mobile chemicals, which generally cannot be

contained in a reliable manner or would present a significant risk to human health

and the environment should exposure occur.

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Air Force Response: Copies of DERM’s letters providing comments on the Streamlined FS, the Proposed Plan, and the Draft Final ROD will be included in Appendix B of this ROD.

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APPENDIX A

REFERENCES

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References

Air Force Base Conversion Agency. Arsenic Background Study. November 1996.

Air Force. Final Voluntary Interim Remedial Actions Report, 21 Miscellaneous Sites, Volume I of III. December 1998.

Booz Allen Hamilton Inc., Final Streamlined Feasibility Study for Operable Unit 25, the Hush House Area, February 2006.

Booz Allen Hamilton Inc., Final Proposed Plan for Operable Unit 25, the Hush House Area, March 2006.

Florida Administrative Code. Chapter 62-777, Contaminant Cleanup Target Levels Rule. 17 April 2005.

IT Corporation. Letter Report CERCLA Five-Year Review Ground-Water Sampling Operable Units 1, 4, 5, 8, 25 and POL Site SS-15C. October 2001.

OHM Remediation Services Corporation. Final Voluntary Interim Remedial Actions Report, 21 Miscellaneous Sites Volume I of III. December 1998.

U.S. Environmental Protection Agency. Risk Assessment Guidance for Superfund: Volume 1, Human Health Evaluation Manual (Part A), Interim Final. December, 1989.

U.S. Environmental Protection Agency. Risk Assessment Guidance for Superfund (RAGS), Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) Interim Final. December 2001.

U.S. Environmental Protection Agency. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. December 2002.

U.S. Environmental Protection Agency. ProUCL Version 3.0 User Guide. April 2004.

U.S. Environmental Protection Agency, Region 9. Preliminary Remediation Goals, User’s Guide/Technical Background Document. December 28, 2004.

Versar, Inc. Draft Letter Report, Year 1 Semi-Annual Monitoring Results, Operable Unit 25. August 1998.

Woodward-Clyde. Final Confirmation Sampling. Report Volume I of IV. November 1995.

Woodward-Clyde. A Practical Approach for the Development of Typical Basewide PAH Concentrations Not Related to Waste Handling Practices for Use in Risk Management Decisions. April 1996.

Woodward-Clyde. Final Report, Site Investigation. AOC 1, AOC 3, AOC 5, OU-19, OUs 20/21, OU-25, O/WS 206. April 1997.

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APPENDIX B

REGULATORY CORRESPONDENCE

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Department of Environmental Protection

Jeb Bush Governor

Twin Towers Building 2600 Blair Stone Road

Tallahassee, Florida 32399-2400 Colleen M. Castille

Secretary

April 28, 2006

Mr. Michael Andre j ko 482"d MSG/CEV 29350 Westover Street Building 232 Homestead ARB, FL 33039-1299

RE: Final Proposed Plan for Operable Unit 25, Hush House Area, Homestead Air Reserve Base, Miami-Dade County, Florida.

Dear Mr. Andre j ko:

I have completed my review of the Final Proposed Plan for Operable Unit 25, Hush House Area, Homestead Air Reserve Base, dated March 2006 (downloaded April 3, 2006), prepared by Booz Allen Hamilton, Inc. While the Department agrees that the selected remedy is acceptable, it cannot agree with all of the reasons stated in the Proposed Plan. The Proposed Plan says that the selected remedy is protective because contaminated soil does not pose a significant risk to current and future anticipated users because the carcinogenic risk for commercial/industria1 workers was less than 1 x and the hazard index was less than 1.0. As I have stated earlier, the Department's acceptable carcinogenic risk is 1 x

The Department's acceptance of the selected remedy of land use restrictions prohibiting residential reuse is based upon the information contained in the Final S i t e I n v e s t i g a t i o n Report f o r AOC 1 , AOC 3 , AOC 5 , OU-19, O U s 2 0 / 2 1 , OU-25 and OWS 206 (Woodward-Clyde, April 1997) , t h e Final V o l u n t a r y I n t e r i m Remedial A c t i o n R e p o r t , 21 Misce l laneous S i t e s (OHM, December 1998) and DERMIS and the Department's previous agreement that No Further Action, other than land use restrictions, is required at the site. I have attached some letters from DERM and FDEP that document this.

Additionally, I will briefly explain my calculations that allowed me to agree with the selected remedy at this site. Based upon our files regarding this site, all soil contaminants except arsenic, lead and chromium were screened out as Contaminants of Potential Concern. With the removal of lead and chromium during Voluntary Interim Remedial Actions only arsenic was left as a Contaminant of Concern. The exposure point concentration for

"More Protection, Less Process "

Printed on recycled paper

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Mr. Andrej ko Page Two April 28, 2006

arsenic in soil, calculated using the 95% Upper Confidence Limit on the mean concentration, as reported in Table 1 of the Proposed Plan indicates that it is less than the Department's industrial soil cleanup target level. For this reason and because of previous correspondence, the Department is accepting the selected remedy for the site.

If you have any concerns regarding this letter, please contact me at (850) 245-8997.

David P. Grabka, P.G. Remedial Project Manager

CC: Tim Bahr, FDEP Doyle Brittain, EPA Region 4, Atlanta Lee Conesa, Northrup Grumman/AFRPA Wilbur Mayorga, DERM Paul Wierzbicki, FDEP Southeast District

Prrnted on recycledpaper.

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Jeb BushGovernor

Department ofEnvi ronmental Protection

Twin Towers Building2600 Blair Stone Road

Tallahassee, Florida 32399-2400

JuLy 13 , 2046

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R E : D r a f t F i n a l - R e c o r d o f D e c i s i o n f o r O p e r a b l e U n i t 2 5 , H u s h

H o u s e A r e a , H o m e s t e a d A i r R e s e r v e B a s e , M i a m i - D a d e C o u n t y ,F L o r i d a .

D e a r M r A n d r o i l z a '

I h a v e c o m p l e t e d m y r e v i e w o f t h e D r a f t F i n a l R e c o r d o fD e c i s i o n f o r O p e r a b l e U n i t 2 5 , H u s h H o u s e A r e a , H o m e s t e a d A i rR e s e r v e B a s e , d a t e d J u n e 2 A A 6 ( d o w n l o a d e d J u n e B , 2 0 0 6 ) , p r e p a r e d

b y B o o z A L l e n H a m i l t o n , T n c . T h e D e p a r t m e n t c a n n o t a g r e e w i t ht h e R e c o r d o f D e c i s i o n a s i t i s c u r r e n t l y w r i t t e n . T h e R O D s a y st h a t t h e c a r c i n o g e n i c r i s k t o c o m m e r c i a l / i n d u s t r i a l w o r k e r s ,c o n s t r u c t i o n w o r K e r s , o r r e s - L d e n t s i s n o L s i g n i f i c a n L b e c a u s e L h oe s t i m a t e d r i s k s c a l c u l a t e d f o r t h e s e r e c e p t o r s a r e l e s s t h a n t h eE P A ' s u a r g e t r i s k r a n g e o I I x

' 1 O - r . T h e D e p a r L m e n r C a n r - o L o o F Q r

w i t h L h a t s r a L e m e n t a s c h e D e p a r t m e n L ' s a c c e p L a b l e c d I c L n o o e n -r i s k l i m i t i s 1 x 1 O - 5 . I f t h e A i r F o r c e c o n t i n u e s t o b a s e i t ss e l e c t e d r e m e d y o n a r a t i o n a l e t h a t d i s r e g a r d s L h e D e p a r L m e n t / sA R A R f o r c a r c i n o g e n i c r i s k , t h e D e p a r t m e n t w i l l n o t b e a b l e t oc o n c u r w i t h t h e F i n a l R O D a s t h a t c o u l d v i o l a t e F l o r i d a S t a t u t e sa n d p o r e n L i a l I y s e L a p r e c e d e n c f o r o t h e r c l e a n u o s o c c u r r i n q i nt h e s t a t e .

P l e a s e n o t e t h a t t h e D e p a r t m e n t h a s p r e v i o u s J - y c o n c u r r e dw i t h t h e s e l e c t e d r e m e d y a t t h i s s i t e f o l l o w i n g a s p e c i f i cr a t i o n a l e . I b e l i e v e i f t h e s t a t e m e n t c o n c e r n i n g t h e E P A ' sf : r n a i r i c k r ;- 3 n g e w e r e t o s p e c i f y t h a t t h a t s t a t e m e n t o n l yp e r t a r n s r o E P A a c c e p t a n c e , L h e s t a t e c o u l d a c c e p t t h e R O D i f t h ef o l l o w i n g p a r a g r a p h w e r e t o b e a d d e d i n S e c t i o n 7 . 4 , p a g e 3 ,a f t e r l i n e 1 2 a n d S e c t i o n 2 . 1 . I , P a g e 2 3 .

"FDEP's acceptable carcinogenic and non-carcinogenic risk are I x I0-n antl uhazard index of 1.0, respectively. Based upon a comparison of contaminantconcentrations in the Site Investigation conducted at Operable Unit 25 withHomestead Air Force Base-speci/ic background concentrations and

"More Pratecrion. Less Process"

Col leen M. Cast i l leSecretary

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M r . A n d r e j k oD r a f t F i n a l R e c o r d o f D e c i s i - o nO p e r a b l e U n i t 2 5P a g e T w oJ u l y 1 3 , 2 0 0 6

industrial/commercial SCTLs, PAHs, including benzo(a)pyrene, and mttst metals

v)ere removed as contaminants of concern. After a Voluntary Interim RemovalAction, only arsenic remained al a.few soil sampling location,s at a concentralionexceeding its industrial/commercial SCTL and background concentration.However, the exposure point concenlralion calculated.for arsenic shown in Tablel-l indicates that it is less than the Departmenl's industrial/commercial SCTL.This indicates that risks.from ar,senic in soil at Operable Unit 25 do not exceed

the Deparlmenl's carcinogenic risk level of' l x l0-" under an industrial/c'ommercial use ,scenario. Bused on lhis, lhe Depurtmenl has ugrcetl thul arutnre,sidential land use control and digging restriction,s would be un ucceptubleremedy./br Operable (lnit 25."

The Reco rd o f Dec i s i on a l so i nd i ca tes t ha t becausenonca rc i nogen i c r i s ks above a haza rd i ndex o f 1 .0 we re ca l cu la tedfo r on -s i t e r es i den t s and cons t ruc t l on wo rke rs , Land Use Con t ro l s(LUCs) p roh ib i t i ng res i den t i a l use and manaq ing so i l d i s t u rbancesa t t he s i t e wou ld be i -mposed . Th i s co r responds we l l w i t h t heDepa r tmen t ' s r equ i remen ts f o r LUCs based on ca rc i nogen i c r i s k asI ' ve w r i t t en above .

I h a v e t h e f o l L o w i n g c o m m e n t s o n t h e r e s t o f t h e r e p o r t :

( 1 ) O n p a g e 6 , p l e a s e r e m o v e t h e l a s t f o u r l i n e s ( l i n e s 1 92 2 ) . T h e D e p a r t m e n t w i l l n o t b e a s i g n a t o r y t o t h e 3 . C D '

R a t h e r , t h e D e p a r t m e n t w i L l p r o v i d e c o n c u r r e n c e a f - - e r ' . : eA i r F o r c e a n d E P A h a v e s r g n e d r t .

( 2 ) O n p a g e 1 8 , o n l i n e s 3 0 , 3 2 , 3 5 , 3 8 a n d 3 9 , t h e E P A ' sM a x i m u m C o n t a m i n a n t L e v e l ( M C L ) i s i n c o r r e c t l y u s e d i n

c o n ; u n c t i o n w i t h t h e D e p a r t m e n t ' s S o i l C l e a n u p T a r q e t L e v e l( S C T L ) . T h i s r s a l s o t h e c a s e o n p a g e i 9 , l i n e 2 . T h e

E P A ' s M C L s a r e a s s o c i a t e d w i t h s t a n d a r d s f o r c o n c e n t r a t t o n so f c o n t a m i n a n t s i n g r o u n d w a t e r . E P A ' s s o i l s c r e e n i n q L e v e f sa r e P r e l i m i n a r V R e m e d i a l G o a l s ( P R G s ) , u s u a l l y E P A ' R e g i o n 9

P R G s .

( 3 ) O n p a g e 2 8 , l i n e s 3 2 a n d 3 3 , p l e a s e r e m o v e t h e l a s t p a r t o f

t h e s e n t e n c e w h i c h r e a d s " a n d b y t h e i r s i g n a t u r e o fc o n c u r r e n c e o n t h i s R O D i n S e c t i o n I . ' 7 . "

( 4 ) P l e a s e i n c o r p o r a t e i n t o t h e R O D t w o f i g u r e s t h a t w i l l s h o ww h e r e t h e n o n - r e s i d e n t i a l l a n d u s e c o n t r o l r e s t r i c t i o n i s t ob e a p p l i e d a n d w h e r e t h e d i g r e s t r i c t i o n i s t o b e a p p l i e d .T h e s e f i q u r e s a r e t o b e i n c o r p o r a t e d i n t o t h e B a s e

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M r . A n d r e j k oD r a f t F i n a l R e c o r d o f D e c i s i o nO p e r a b l e U n i t 2 5P a g e T h r e eJ u l y 7 3 , 2 A A 6

c o - r n - e h o ^ s i r r e P l a n a n d o t h e r l a n d u s e m a n a g e m e n t d o c u m e n t s

t o s h o w w h e r e t h e r e s t r i c t i o n s a r e .

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August 31, 2006 4WD-FFB EMAIL & US MAIL Lawrence Ventura, Environmental Flight Chief Homestead Air Reserve Base 482d SPTG/CEV 360 Coral Sea Blvd. Homestead ARB, FL 33039-1299 SUBJ: EPA Comments on the Redline Strikeout of the OU 25 ROD Homestead Air Reserve Base, Florida Dear Mr. Ventura: The Environmental Protection Agency (EPA) has reviewed the subject document and offers the enclosed comments. If you have any questions, please call me at (404) 562-8549. Sincerely, Doyle T. Brittain Senior Remedial Project Manager Enc. cc: Carol Devier-Heeney, AFRPA/DA Lee Conesa, HAFB/AFRPA Philippe Montaigne, HQ AFRC/CEVX David Grabka, FDEP Martha Brock, EPA/EAD

Page 64: RECORD OF DECISION FOR OPERABLE UNIT 25 HUSH ...1 HOMESTEAD AIR RESERVE BASE HOMESTEAD, FLORIDA RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA 1.0 DECLARATION 1.1 Site

August 31, 2006 4WD-FFB EMAIL & US MAIL Lawrence Ventura, Environmental Flight Chief Homestead Air Reserve Base 482d SPTG/CEV 360 Coral Sea Blvd. Homestead ARB, FL 33039-1299 SUBJ: EPA Comments on the Redline Strikeout of the OU 25 ROD Homestead Air Reserve Base, Florida Dear Mr. Ventura: The Environmental Protection Agency (EPA) has reviewed the subject document and offers the enclosed comments. If you have any questions, please call me at (404) 562-8549. Sincerely, Doyle T. Brittain Senior Remedial Project Manager Enc. cc: Carol Devier-Heeney, AFRPA/DA Lee Conesa, HAFB/AFRPA Philippe Montaigne, HQ AFRC/CEVX David Grabka, FDEP Martha Brock, EPA/EAD D.Brittain/dtb:4WD-FFB:28549:08-30-06:C:\My Documents\HAFB\OU 25, ROD EPA Comments on Redline Strikeout, 08-30-06 D.BRITTAIN FL/AL/MS Fed. Oversight Section

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ENVIRONMENTAL PROTECTION AGENCY COMMENTS ON THE REDLINE STRIKEOUT FOR OU 25

EPA Comment 7. On page 5, lines 3-4 and 10, please add “report on” to the list of EPA Comment 11. On page 5, lines 27-28, please restore the first part of the sentence, to CERCLA § 121(b). EPA Comment 24. Page 26, lines 24-28. Please move this text to the end of the section. Delete “However,” on line 28 and add “the” before “remedial action.” EPA Comment 28. Page 31, lines 11-16. Do we have data? If not, then state that, while keeping the description of the qualitative measures. EPA Comment 34. Page 36, line 8. The Air Force omitted the following text, proposed by EPA to be included in the BGP:

No construction or digging is allowed without prior approval by the base Engineer in the form of a dig permit or other approval as required. Dig permits shall specify in writing required protective measures to prevent unacceptable exposure to construction workers to contaminants in the surface or subsurface soil, for instance, total PAHs or benzo(a)pyrene in excess of 700 Fg/kg or arsenic in excess of 12 Fg/kg.

Please include this language. Page 36, line 36. The Air Force added “by the Air Force” after “determined,” in the phrase, “any additional LUC determined to be necessary.” Please delete “by the Air Force.” The Air Force and EPA, with concurrence by the State, are selecting this CERCLA remedy. Any future changes to this remedy will be made by those parties. If the Air Force wishes to restrict uses of the property in ways not directly tied to CERCLA, then this ROD is not relevant to those restrictions and should not be used to describe them. EPA Comment 35. Please add the requested language at what is now page 35, line 8, after “2-8.” EPA Comment 38. Please add the requested language at what is now page 37, line 14, at the beginning of the paragraph. New Comment 1. Section 1.4, page 5, line 3. Please delete “residential,” since all use restrictions (not just

residential use restrictions) identified as requiring LUCs selected in this ROD should be identified in the BGP.

2. Section 2.12, page 37, line 32. Please delete “begin.” 3. Section 2.12, page 47, line 8. Please change "may" to "will."

Page 66: RECORD OF DECISION FOR OPERABLE UNIT 25 HUSH ...1 HOMESTEAD AIR RESERVE BASE HOMESTEAD, FLORIDA RECORD OF DECISION FOR OPERABLE UNIT 25 – HUSH HOUSE AREA 1.0 DECLARATION 1.1 Site

1% 1PT: tlTID#

&* Department of

* - @fl Environmental Protection ~ F L O R I A

Jeb Bush Governor

Twin Towers Building 2600 Blair Stone Road

Tallahassee, Florida 32399-2400 Colleen M. Castille

Secretary

September 8, 2006

Mr. Michael Andre j ko 482nd MSG/CEV 29350 Westover Street Building 232 Homestead ARB, FL 33039-1299

RE: Draft Redline/Strikeout Record of Decision for Operable Unit 25, Hush House Area, Homestead Air Reserve Base, Miami-Dade County, Florida.

Dear Mr. Andrej ko:

I have completed my review of the Draft Redline/Strikeout Record of Decision for Operable Unit 25, Hush House Area, Homestead Air Reserve Base, dated August 2006 (downloaded August 18, 2006), prepared by Booz Allen Hamilton, Inc. I have the following comments on this redline/strikeout version of the Record of Decision:

(1) The maximum detected concentration in Table 2-5 of Total PAHs, which are actually the calculated benzo(a)pyrene toxicity equivalents, does not match the highest Total PAH values listed in Tables 2-2 and 2-3.

(2) In the section on State Acceptance on page 32, please also add that the calculated exposure point concentration for arsenic is also less than the accepted Homestead Air Force Base-specific arsenic background concentration of 10 mg/kg.

If you have any concerns regarding this letter, please contact me at (850) 245-8997. Dd)$$&

David P. Grabka, P.G. Remedial Project Manager

CC: Tim Bahr, FDEP Doyle Brittain, EPA Region 4, Atlanta Lee Conesa, Northrup Grumman/AFRPA

"More Protection, Less Process"

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Mr. Andrej ko Page Two September 8, 2006

Wilbur Mayorga, DERM Paul Wierzbicki, FDEP Southeast District

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